JERUSALEM -- The surprising victory of a reformist candidate in Iran's presidential election has put Israel in a difficult position as it tries to halt the Iranian nuclear program: With Hasan Rowhani likely to enjoy an international honeymoon, Israel could have a hard time rallying support for new sanctions – or possible military action – against its arch foe, even as it says the clock is ticking on Tehran's march toward nuclear weapons.

The uncertainty facing Israel was evident Sunday in the reactions among its leaders, who welcomed the signs of change in Iran while also warning the world should not be fooled.

"Let us not delude ourselves. The international community must not become caught up in wishful thinking and be tempted to relax the pressure on Iran to stop its nuclear program," Prime Minister Benjamin Netanyahu said.

Rowhani swept to a landslide victory in Friday's election with a call for outreach and dialogue with the international community. His predecessor, Mahmoud Ahmadinejad, repeatedly clashed with the West over the nuclear issue, isolating the country and drawing several rounds of painful economic sanctions. Rowhani's victory was widely seen as a show of discontent with Ahmadinejad and Iran's hardline clerical establishment.

While Rowhani is considered a relative moderate and had the backing of Iranian reformists, the hardline supreme leader Ayatollah Ali Khamenei remains the ultimate authority on all state matters, including the nuclear program.

Israel, along with major Western countries, suspects that Iran is developing the infrastructure that would allow it to make a nuclear bomb. Although Israel believes Iran has not reached weapons capability, Netanyahu has warned that Iran is inching perilously close to the "red lines" where the nuclear program could no longer be stopped.

Israeli leaders have welcomed the sanctions, which have fueled double digit unemployment and inflation in Iran. But they say the economic pressure isn't enough, and that military action cannot be ruled out. Netanyahu has called on the international community to present a "credible" military threat to Iran, and hinted that Israel might even strike alone if it feels threatened.

Speaking to his Cabinet, Netanyahu noted that Khamenei had disqualified many more moderate candidates, and that Rowhani has made hostile comments about Israel. He also said that Khamenei still oversees nuclear policy.

"The more the pressure on Iran increases, the greater is the chance of stopping the Iranian nuclear program, which remains the greatest threat to world peace," he said. "Iran will be judged by its actions. If it continues to insist on developing its nuclear program, the answer needs to be very clear – stopping the nuclear program by any means."

Israel considers a nuclear-armed Iran to be a threat to its very existence, citing its support for militant groups on Israel's doorstep, such as Hamas and Hezbollah, its calls for the destruction of the Jewish state and its development of sophisticated missiles capable of hitting it. Tehran insists its nuclear program is for peaceful purposes only.

Israeli President Shimon Peres took a softer line than Netanyahu, saying the results amounted to a massive show of disapproval with Khamenei and Ahmadinejad.

"More than half of Iranians, in their own way, in my judgment, protested against an impossible leadership," Peres, a Nobel peace laureate, told The Associated Press in an interview. "It is clearly a voice of the people and a voice that says, `We don't agree with this group of leaders.'"

While saying it is impossible to predict the future, he said the vote was a "new beginning" that could pave the way for a peaceful resolution to the nuclear standoff.

When Rowhani was Iran's chief nuclear negotiator a decade ago, Iran temporarily suspended all uranium enrichment-related activities to avoid possible sanctions from the U.N. Security Council. Enriched uranium is a key component in building a bomb, though it does have other purposes as well.

Israeli analysts were divided over whether having a more moderate Iranian president might actually weaken Israel's military option by making it harder to confront Iran.

Meir Litvak, head of Iranian studies at Tel Aviv University, told Israel Army Radio that Rowhani's "smiley face to the West" might make the option of military action less likely.

But Eldad Pardo, an Iran expert at Hebrew University in Jerusalem, said he didn't believe Israel would worry about public approval if it decides nuclear action is needed. More important, he said, was whether the U.S. and the U.N. nuclear agency can make progress with the new Iranian government.

"Generally speaking, I think that a different political culture in Iran is a good thing for Israel and it is good for Iran," he said.

Uzi Arad, Netanyahu's former security adviser, said that Rowhani's taking over might be good for Israel.

Arad told Israel Radio that it was a good sign that millions of Iranians voted for a candidate who "explicitly spoke about acting to ease sanctions and strive for talks with the West."

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  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani (portrait) in the presidential elections at Vanak square in northern Tehran on June 15, 2013. Iranian Interior Minister Mohammad Mostafa Najjar said Rouhani won outright with 18.6 million votes, or 50.68 percent. (ATTA KENARE/AFP/Getty Images)

  • Passengers in a public bus flash victory signs in a reaction of supporters of the Iranian presidential candidate Hassan Rouhani, as they attend a celebration gathering, in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A supporter of Iranian presidential candidate Hassan Rouhani, shown in poster, attends a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • Supporters of the Iranian presidential candidate Hassan Rouhani, shown in poster at center, attend a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A female supporter of Iranian presidential candidate Hassan Rouhani flashes a victory sign as she holds his poster during a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • Supporter of the Iranian presidential candidate Hassan Rouhani celebrate outside his campaign headquarters in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A female supporter of Iranian presidential candidate Hassan Rouhani, flashes a victory sign as she holds his poster during a celebration gathering in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • A supporter of Iranian presidential candidate Hassan Rouhani holds his poster as another youth waves to a clergyman outside the campaign headquarters of Rouhani, in Tehran, a day after the election, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • An Iranian woman flashes the sign for victory as she holds a portrait of moderate presidential candidate Hassan Rouhani during celebrations for his victory in the Islamic Republic's presidential elections in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians supporters of moderate presidential candidate, Hassan Rouhani flash the sign of victory holding a portrait of him as they wait for the final results outside his campaign headquarter in downtown Tehran on June 15, 2013. Rouhani has a clear lead in Iran's presidential election, garnering 51 percent of the vote at 65 percent of polling stations across the country, the interior ministry said. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian woman holds a portrait of moderate presidential candidate Hassan Rouhani as she rides on a motorcycle along Valiasr street in Tehran on June 15, 2013 after he was elected as president. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian woman holds her purple scarf, the campaign color of moderate presidential candidate Hassan Rouhani, as she celebrates along Valiasr street after he was elected as president on June 15, 2013, in the capital Tehran. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians gather as they celebrate the victory of moderate presidential candidate Hassan Rouhaniin the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. Iranian Interior Minister Mohammad Mostafa Najjar said Rouhani won outright with 18.6 million votes, or 50.68 percent. (ATTA KENARE/AFP/Getty Images)

  • Iranian supporters of moderate presidential candidate Hassan Rouhani who won the national elections, celebrate in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians celebrate along Valiasr street, in the capital Tehran, on June 15, 2013, after moderate presidential candidate Hassan Rouhani was elected as president. (BEHROUZ MEHRI/AFP/Getty Images)

  • An Iranian woman celebrates the victory of moderate presidential candidate Hassan Rouhani (portrait) in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani (portrait) in the Islamic Republic's presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani (portrait) in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians gather to celebrate the victory of moderate presidential candidate Hassan Rouhani in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • An Iranian woman celebrates the victory of moderate presidential candidate Hassan Rouhani in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians gather as they celebrate the victory of moderate presidential candidate Hassan Rouhani in the presidential elections at Vanak Square, in northern Tehran, on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranian women hold a portrait of moderate presidential candidate Hassan Rouhani who won the national election in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • A female supporter of Iranian presidential candidate Hasan Rouhani flashes a victory sign, as she holds his poster, during a celebration gathering, in Tehran, Iran, Saturday, June 15, 2013. (AP Photo/Vahid Salemi)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rowhani (portrait) in the Islamic Republic's presidential elections in downtown Tehran on June 15, 2013. (BEHROUZ MEHRI/AFP/Getty Images)

  • In front of a portrait of the late Iranian revolutionary founder Ayatollah Khomeini, presidential candidate Hasan Rowhani, a former top nuclear negotiator, center, gestures to his supporters at a rally in Tehran, Iran, Saturday, June 1, 2013. (AP Photo/Ebrahim Noroozi, File)

  • An Iranian woman holds a portrait of moderate presidential candidate Hassan Rouhani as she rides on a motorcycle along Valiasr street in Tehran on June 15, 2013 after he was elected as president. (BEHROUZ MEHRI/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rouhani in the Islamic Republic's presidential elections at Vanak square in northern Tehran on June 15, 2013. (ATTA KENARE/AFP/Getty Images)

  • Iranians celebrate the victory of moderate presidential candidate Hassan Rowhani (portrait) in the Islamic Republic's presidential elections at Vanak square in northern Tehran on June 15, 2013. (ATTA KENARE/AFP/Getty Images)