"The situation is different and much more difficult than the previous time, lots of things should be done by the other side to buy our confidence," Araghchi said in a video of an interview with Sky News posted to his official Telegram channel Tuesday.

During his first term, US President Donald Trump pursued a policy of "maximum pressure" towards Iran, withdrawing from a landmark 2015 deal that imposed curbs on Iran's nuclear programme in return for sanctions relief.

Following the withdrawal, the United States reimposed biting sanctions on Tehran, prompting the Islamic republic to begin rolling back its commitments, including by increasing its level of uranium enrichment.

"There should be enough confidence for Iran to once again engage in negotiations, and I think we are still far from that," Araghchi said in the interview.

"We haven't heard anything but the nice words (from the new US administration) and this is obviously not enough."

On Thursday, Trump said he wished to avoid military strikes on Iran's nuclear facilities, hoping instead for an agreement.

"Any attack against our nuclear facilities would be faced with an immediate and decisive response," Araghchi said, adding such a move would be "crazy", and would "turn the region into a very bad disaster".

Iran's supreme leader Ayatollah Ali Khamenei, who has the final say in all matters of state, also warned on Tuesday that "behind the smiles of diplomacy, there are enmities, grudges, and evil intentions".

"We should open our eyes and be careful who we are facing, dealing with, and talking to," he added, without referring to the United States.

Iran has repeatedly expressed willingness to revive the nuclear deal, and President Masoud Pezeshkian, who took office in July, has called for an end to his country's isolation.

However, Iranian Deputy Foreign Minister Majid Takht-Ravanchi said Monday that there had been no exchanges between Iran and the US since Trump returned to the White House.