"Ultimately, what we want to see from Iran is actual behavioural change and action, not just signs of something or indications of something," said State Department spokesman Vedant Patel, part of the outgoing administration of President Joe Biden.

"We want to ensure that Iran never has a nuclear weapon, and we're going to continue to use a variety of tools to pursue that goal, and all options remain on the table," Patel told reporters.

Pezeshkian made the comments during a visit to Tehran by the head of the UN nuclear watchdog, Rafael Grossi.

The president, considered a moderate within the clerical state, said Iran was ready to "resolve the alleged ambiguities and doubts about the peaceful nuclear activity of our country."

Trump in his last term sought "maximum pressure" on Iran and withdrew from a nuclear deal negotiated under his predecessor Barack Obama, although he has recently said he is open to diplomacy with Tehran.

Israel has ramped up pressure on Iran including through direct military strikes, with Defense Minister Israel Katz recently warning that Iran is "more exposed than ever to strikes on its nuclear facilities."