The war of words on Monday came as the semi-official Tasnim news agency announced Iran has, in line with an earlier decision, scaled back some of its commitments under the 2015 nuclear deal.
“Iranians have stood tall for millennia while aggressors all gone. Economic terrorism and genocidal taunts won’t ‘end Iran’,” Mohammad Javad Zarif, Iran’s foreign minister, wrote on Twitter.
“Never threaten an Iranian. Try respect – it works!” he added.
The riposte followed a Twitter post by Trump, who told Iran not to threaten the US.
“If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again,” he wrote on Sunday, without clarifying what threats he meant.
Trump doubled down on Monday, saying Iran would be met with “great force” if it attempted anything against US interests in the Middle East. But while arguing that Tehran had been very hostile towards Washington, the US president told reporters as he departed the White House that he was still willing to have talks with Iran “when they’re ready”.
Hours later, Iranian President Hassan Rouhani said he favoured talks and diplomacy but not under the existing conditions.
“Today’s situation is not suitable for talks and our choice is resistance only” state news agency IRNA quoted Rouhani as saying late on Monday.
Relations between Washington and Tehran plummeted a year ago when Trump pulled the US out of the Joint Comprehensive Plan of Action (JCPOA), an international accord that offered Iran sanctions relief in exchange for curbs on its nuclear programme.
Since exiting the landmark deal, Trump has tightened sanctions on Tehran and moved to cut its oil production to zero.
Rouhani responded to the US moves earlier this month, saying his country would no longer observe limits the deal imposed on its stockpiles of low-enriched uranium.
Under the pact, Tehran was allowed to stockpile a maximum of 300kg of low-enriched uranium and was required to ship any excess out of the country for storage or sale.
The agreement also allowed Iran to enrich uranium at 3.67 percent – a rate suitable for civilian nuclear power generation but far below the 90 percent of weapons-grade.
Iran has threatened to gradually withdraw from the 2015 nuclear deal if partners still in the agreement – the United Kingdom, China, France, Germany and Russia – do not help it to circumvent US sanctions.
On Monday, both the semi-official Fars and Tasnim news agencies reported on the quadrupled production of low-enriched uranium, quoting Behrouz Kamalvandi, spokesman for Iran’s nuclear agency.
Kamalvandi told Tasnim that the United Nations atomic watchdog, the International Atomic Energy Agency (IAEA), has been notified of the move.
“It won’t be long until we pass the 300-kg limit of low enriched uranium. So it’s better for the other side to do what it’s necessary to be done,” he said, alluding to steps by other powers to shield Iran’s economy from US sanctions.
Kamalvandi said the acceleration of Iran’s centrifuge enrichment machines remained within the bounds of the nuclear deal, adding that Tehran has no intention to exit the accord.
“We are on a clock,” said Al Jazeera’s Zein Basravi, noting that Rouhani had given the pact’s remaining signatories 60 days to act on salvaging the nuclear deal. “If this path continues, then it is a clear sign Iran is serious about non-cooperation with the JCPOA and may eventually pull out entirely.”
Ali Fathollah-Nejad, visiting fellow at Brookings Institute in Doha, described Iran’s move to increase low-enriched uranium production as “a gradual effort by Iran towards re-establishing the kind of leverage” it had when it entered into negotiations with the US in 2012.
“It is aimed at showing the international community, the US in particular, that Iran is not in a position of weakness. However, this is also a risky endeavour, because it might jeopardise the political and diplomatic support that until now Iran has received from Europe,” he said from Berlin.
The Iranian move to resume uranium enrichment follows days of heightened tensions sparked by the Trump administration’s deployment of bombers and an aircraft carrier to the Gulf over as-yet-unspecified threats from Iran.
Last week, Washington also ordered its non-essential diplomatic staff out of Iraq, citing dangers posed by Iran-backed Iraqi armed groups.
On Sunday, a rocket was fired into the Green Zone of the Iraqi capital, Baghdad, which houses government offices and embassies including the US mission. It was not immediately clear who was behind the attack.
Iraqi leaders warned on Monday against dragging their country into a possible war between the US and Iran.
“We need peace and construction and any party who drags Iraq into war and turns it into a battlefield will be the enemy of the Iraqi people,” he said.
While the US claim of Iranian “threats” has been met with widespread scepticism outside the US, the rising rhetoric and tensions have sparked growing international concern.
Stephane Dujarric, spokesman for UN, called on “all parties to lower rhetoric and lower the threshold of action as well”.
Jeremy Hunt, Britain’s foreign secretary, told journalists in Geneva that Iran should not doubt the US’s resolve, warning that “if American interests are attacked, they will retaliate”.
“We want the situation to de-escalate because this is a part of the world where things can get triggered accidentally,” he said.
Meanwhile, Oman’s minister of state for foreign affairs made a previously unannounced visit on Monday to Tehran, where he held talks with Zarif, the state-run IRNA news agency reported. The visit by Yusuf bin Alawi came after US Secretary of State Mike Pompeo called Oman’s Sultan Qaboos bin Said last week.
Oman has long served as a Western backchannel to Tehran and the sultanate hosted the secret talks between the US and Iran that laid the groundwork for the nuclear deal negotiations.
‘Goaded into war’
US media reports say Trump’s hawkish National Security Adviser John Bolton is pushing for war with Iran, but others in the administration are resisting.
Zarif’s tweet said Trump is being “goaded by #B Team”, a term he coined to refer to Bolton as well as Israel’s prime minister, Benjamin Netanyahu, known as Bibi and the crown princes of Saudi Arabia and the United Arab Emirates, Mohammed bin Salman (MBS) and Mohammad bin Zayed, who are all pushing a hard line on Tehran.
Saudi Arabia on Saturday called for emergency regional talks to discuss the mounting Gulf tensions.
It came days after mysterious sabotage attacks on several tankers in highly sensitive Gulf waters and drone attacks on a Saudi crude pipeline by Yemen rebels who Riyadh claimed were acting on Iranian orders.
Iran has denied any involvement in the incidents.
Saudi Arabia’s minister of state for foreign affairs, Adel al-Jubeir, said on Sunday his country does not want to go to war with Iran but would defend itself.
On Monday, Iran sent a letter to UN Secretary-General Antonio Guterres asking him to launch direct talks between Tehran and other Gulf states to ease tensions.