"You should not negotiate with such a government, it is unwise, it is not intelligent, it is not honourable to negotiate," Khamenei said during a meeting with army commanders.

The United States had previously "ruined, violated, and tore up" a 2015 nuclear deal, he said, adding that "the same person who is in power now tore up the treaty".

On Wednesday, Trump suggested striking a "verified nuclear peace agreement" with Iran, adding in his social media post that Tehran "cannot have a Nuclear Weapon".

Trump, who returned to the White House on January 20, reinstated on Tuesday his "maximum pressure" policy towards Iran over allegations the country is seeking to develop nuclear weapons.

Iran insists its nuclear programme is solely for peaceful purposes and denies any intention to develop atomic weapons.

Following the policy's reinstatement, Washington on Thursday announced financial sanctions on entities and individuals accused of shipping hundreds of millions of dollars' worth of Iranian crude oil to China.

Iran condemned the sanctions on Friday as "illegal", saying they were "categorically unjustified and contrary to international rules".

"We must understand this correctly: they should not pretend that if we sit down at the negotiating table with that government (the US administration), problems will be solved," Khamenei said.

"No problem will be solved by negotiating with America," he said, citing previous "experience".

- Reciprocity -

Khamenei went on to warn that Iran would take reciprocal measures if the US threatened or acted against Iran.

"If they threaten us, we will threaten them. If they carry out this threat, we will carry out our threat. If they attack the security of our nation, we will attack their security without hesitation," Khamenei said.

During Trump's first term, which ended in 2021, Washington withdrew from the landmark nuclear deal that had imposed curbs on Iran's nuclear programme in return for sanctions relief.

Tehran adhered to the 2015 deal -- known as the Joint Comprehensive Plan of Action -- until a year after Washington pulled out, but then began rolling back its commitments. Efforts to revive the deal have since faltered.

Khamenei said Iran was "very generous" during the negotiations that culminated in the deal, but it "did not achieve the intended results."

Western sanctions, especially since the US withdrawal from the nuclear deal, have taken a toll on millions of Iranians struggling to make ends meet amid high inflation and a plunging currency.

During the meeting, Khamenei acknowledged the people's struggles, saying "almost most segments of the population have some problems" but adding they could be solved internally.

The current "respected government can reduce the livelihood problems of the people", he said.