President Barack Obama addressed Iran during a press conference on Thursday called to address issues with Obamacare.
"I've said before and I will repeat -- we do not want Iran having nuclear weapons," Obama said when asked about Iran by Agence France-Presse's Stephen Collinson.
Iran has virtually halted the expansion of its uranium enrichment capacity in the past three months, the U.N. nuclear agency said in a report roughly covering the period since Hassan Rouhani became president.
The quarterly report by the International Atomic Energy Agency (IAEA) also showed that Iran's stockpile of higher-grade enriched uranium - closely watched by the West and Israel - had risen by about 5 percent to 196 kg since August.
But it still remained below the roughly 250 kg needed for a bomb if refined further to weapons grade. Iran rejects Western and Israeli accusations that it is seeking nuclear weapons capability.
Obama said the core sanctions on Iran would be left in place to test how serious they are about halting the country's nuclear program.