The supreme leader of Iran has told Donald Trump he has "made a mistake" over his heavily-criticised decision to pull the US out of the country's nuclear deal.
Ayatollah Ali Khamenei accused the US President of telling "more than 10 lies" during his announcement speech on Tuesday, adding that he had threatened the people of Iran and its government.
"You heard last night that the president of America made some silly and superficial comments," Mr Khamenei said in a statement on his official website on Wednesday.
"He had maybe more than 10 lies in his comments. He threatened the regime and the people, saying I'll do this and that.
"Mr Trump I tell you on behalf of the Iranian people: you've made a mistake. You cannot do a damn thing."
Iran's Islamic Republic and theocratic government ensures that Mr Khamenei has the final say on all state matters.
During his White House address, Mr Trump called the Joint Comprehensive Plan of Action (JCPOA) "disastrous" and "one-sided".
He said no action taken by Iran had been more dangerous than its pursuit of nuclear weapons, and claimed the deal had allowed Iran to enrich uranium and "cause havoc within the Middle East and beyond".
The 2015 agreement was made by Iran and the US, the UK, Russia, France, China, Germany and the EU to ensure Iran's nuclear programme was "exclusively peaceful".
In return, the US agreed to lift a range of nuclear-related sanctions, which Mr Trump will now reimpose.
Under the deal, spearheaded by Barack Obama, Iran stopped producing 20% enriched uranium and gave up the majority of its stockpile in return for most international sanctions on it being lifted.
President Hassan Rouhani warned that Iran was ready to resume its nuclear activities if its interests were not guaranteed under a deal without the United States.
"If needed, we will resume our nuclear enrichment at the industrial level without any limit," he said.
Britain and its key European allies – who expressed their "regret and concern" over Mr Trump's decision in a joint statement on Wednesday – have been left scrambling to keep the deal alive.
Foreign Office Minister Alistair Burt told the BBC Radio 4 Today programme there was a need to de-escalate tensions in the wake of Mr Trump's warning that he was ready to impose the "highest level" of sanctions on Tehran.
According to the US Treasury, sanctions related to Iran's energy, auto and financial sectors will be reimposed in three to six months.
The speaker of the Iranian parliament – where US flags were burned in the wake of the announcement – said there was now a window in which the EU could demonstrate whether it had the international clout to keep the agreement going.
Germany's foreign minister Heiko Mass has vowed to work to preserve the deal and prevent an "uncontrolled escalation" of tensions in the Middle East
The Iran deal was seen as one of the Obama administration's key foreign policy achievements.
"I believe that the decision to put the JCPOA at risk without any Iranian violation of the deal is a serious mistake," the former president said in a statement.
"Without the JCPOA, the United States could eventually be left with a losing choice between a nuclear-armed Iran or another war in the Middle East."
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Russia's deputy UN ambassador Dmitry Polyanskiy said Moscow was "disappointed" but "not surprised" by the move, which has also been criticised by the Chinese foreign ministry.
But Israeli Prime Minister Benjamin Netanyahu praised a "brave and correct" decision.