"She is fine now, she is really healthy," Alsabah, 54, told The Associated Press by telephone from Britain. She said the girl had been at the Saudi embassy in Tehran for months after she ran away from her Iranian guards.
Many of bin Laden's children escaped to Iran after the 2001 U.S.-led invasion of Afghanistan. Several siblings lived in a walled compound under Iranian guard after authorities picked them up for entering the country illegally.
"They had traveled on Sudanese passports," Alsabah said. "Their names had been altered by the Sudanese government so it was impossible for them to be identified.
The Iranians treated Iman and her siblings well but they lived in isolation, with only occasional, escorted trips out of the compound, she added.
"About two years ago, Iman, who was 15 at the time, started to deeply miss her mum," Alsabah said. She said the Iranian government had been allowing Iman to call her mother, Najwa.
Osama bin Laden was 17 when he married Najwa, his Syrian first cousin, who was 15 at the time. On Sept. 9, 2001, Najwa left her husband and returned to Syria, taking with her a son and her two youngest daughters. Iman was left behind with her father and siblings.
Omar bin Laden, who was 20 then, had left the family and Afghanistan earlier that year.
Now 29, Omar is urging countries to give refuge to family members still being held in Tehran.
He said there are at least four other siblings and 25 other relatives, among them bin Laden's daughters-in-law and 11 grandchildren.
"They need to live a normal life, in a human way," he told the AP. "They have nothing to do with violence."