Donald Trump is not mentally fit for his job, the speaker of Iran's parliament says, in Tehran's most personal criticism since the US president's decision to withdraw from a 2015 nuclear pact between Tehran and six world powers.
Trump pulled the US out of the deal on Tuesday, raising the risk of conflict in the Middle East, upsetting European allies and casting uncertainty over global oil supplies.
"Trump does not have the mental capacity to deal with issues," parliament speaker Ali Larijani told the assembly, broadcast live on state TV.
Members of parliament burned an American flag and a symbolic copy of the Iran deal, known officially as the Joint Comprehensive Plan of Action (JCPOA), as a session of parliament began on Wednesday.
They also chanted "Death to America".
"Trump's abandoning of the nuclear deal was a diplomatic show ... Iran has no obligation to honour its commitments under the current situation," Larijani said.
"It is obvious that Trump only understands the language of force."
General Mohammad Baqeri, the chief of staff of Iran's military, said Iran did not have to sign the deal. "But that arrogant country (America) did not even stand by its signature," the Islamic Republic News Agency (IRNA) quoted him as saying.
President Hassan Rouhani said on Tuesday Iran would remain committed to the deal without Washington despite Trump's decision to withdraw from it. The pact was designed to deny Tehran the ability to build nuclear weapons.
"If we achieve the deal's goals in cooperation with other members of the deal, it will remain in place. ... By exiting the deal, America has officially undermined its commitment to an international treaty," Rouhani said in a televised speech.
"I have ordered the foreign ministry to negotiate with the European countries, China and Russia in coming weeks. If at the end of this short period we conclude that we can fully benefit from the JCPOA with the cooperation of all countries, the deal would remain," he said.
Under the deal, struck between Iran, the US, Russia, China, Britain and France and Germany, Tehran curbed its nuclear program in return for them lifting sanctions.
Trump said he would reimpose economic sanctions on Tehran immediately.
His decision puts pressure on his European allies, which are key backers of the deal and are reluctant to join the US in reimposing sanctions on Iran.
Trump's decision could tip the balance of power in Iran in favour of hardliners looking to constrain Rouhani's ability to open up to the West.
Iran's supreme leader, Ayatollah Ali Khamenei, has said Iran would "shred" the deal if the US pulled out.
Rouhani warned that Iran was ready to resume its curbed nuclear activities if Iran's interests were not guaranteed under a deal without the US.
"If needed, we will resume our nuclear enrichment at the industrial level without any limit," Rouhani said.