Iran's supreme leader on Thursday lashed out against US President Donald Trump describing the speech he delivered at the UN this week as full of "gangster and cowboy" rhetoric.
"The reason behind the foolish, very ugly, insolent and disorderly speech with cowboy and gangster wording... is their anger (and) desperation," Ayatollah Ali Khamenei said in reference to Trump and the US administration.
In remarks to a top clerical body, the Assembly of Experts, carried by his website, Khamenei described Trump and the US administration as "having no brains".
"The US president's remarks are not a source of pride for the American nation and the elite of that country should feel ashamed of... having such a president," Khamenei said.
The Assembly of Experts is a body of elected clerics that oversees the functions of the supreme leader and has constitutional powers to select and even dismiss the leader.
Trump delivered a scathing verbal attack against Iran in his maiden speech to the UN General Assembly on Tuesday.
The US president referred to the Islamic republic as a "murderous regime" and a "depleted rogue state whose chief exports are violence, bloodshed and chaos".
Tensions between Tehran and Washington have increased under Trump's administration.
Washington and Tehran's top diplomats confronted each other for the first time Wednesday as envoys scrambled to save the Iran nuclear deal from a sceptical Donald Trump.
US Secretary of State Rex Tillerson and Iranian Foreign Minister Mohammad Javad Zarif met as signatories to the 2015 accord at an EU-hosted event on the sidelines of the UN General Assembly.
European ministers called the meeting to examine ways to save a deal that US President Trump is poised to denounce, but Tehran and Washington remain far apart.
EU foreign policy chief Federica Mogherini put the bravest possible face on the encounter, stressing that Iran and the major powers agree the deal is "delivering."
But Tillerson said the discussion had been a political one and that even if Iran is in "technical" compliance with the pact, "significant differences" remain.
Speaking to Iran's state broadcaster after the meeting, Zarif said all "members, except one country, stressed the importance of fully observing the (deal), its being non-negotiable and that all sides should remain committed to this international achievement."
He condemned Washington's "verbosity, especially the very insolent remarks by the president of the country".