US President Donald Trump said on Thursday he wanted "direct talks" with Tehran on a nuclear deal, after he threatened to bomb Iran if it develops nuclear weapons.

Trump has given Iran's leaders a two-month deadline to reach an agreement on the country's nuclear programme, which has strained relations with Western nations for decades.

Western countries, including the United States, have long accused Iran of pursuing a nuclear weapon, which Tehran has denied, insisting its enrichment activities were solely for peaceful purposes.

"I think it's better if we have direct talks," he told reporters onboard the presidential plane Air Force One.

"I think it goes faster and you understand the other side a lot better than if you go through intermediaries."

Iran's Foreign Minister Abbas Araghchi said last week that Tehran would not engage in direct talks with Washington "until there is a change in the other side's approach towards the Islamic Republic."

Trump in his first term ripped up a 2015 nuclear deal negotiated by predecessor Barack Obama and reimposed crippling sanctions on Iran.

The deal, sealed between Tehran and world powers, had required Iran to limit its nuclear ambitions in exchange for sanctions relief.

"They wanted to use intermediaries, I don't think that's necessarily true anymore," Trump said.

"I think they're concerned, I think they feel vulnerable. I don't want them to feel that way," he added.

"I think they want to meet."

Trump said last month he had written to Iran's supreme leader Ayatollah Ali Khamenei to call for nuclear negotiations and warn of possible military action if Tehran refused.

Khamenei responded by saying that US threats "will get them nowhere" and warned of reciprocal measures "if they do anything malign" against Iran.

Trump last week said "there will be bombing" of Iran if it does not drop its efforts to develop nuclear weapons.

Trump's outreach comes at a weak point for the Islamic Republic after Israel decimated two of its allies – Hamas, the Palestinian militants who attacked Israel on October 7, 2023, and Lebanon's Hezbollah. (AFP)