European powers on Thursday rejected “ultimatums” from Tehran but vowed to fight to save the Iran nuclear deal, as tensions with the US soar.

Iran said it would defy some restrictions agreed under the 2015 accord and threatened to go further if Europe, China and Russia fail to deliver sanctions relief within 60 days.

Tehran says it is responding to unilateral US sanctions imposed by Washington after President Donald Trump ripped up what he called a “horrible” deal, dealing a severe blow to the Iranian economy.

Europe has stressed the importance of the deal for its own security.

EU diplomatic chief Federica Mogherini and France, Germany and Britain – the three European signatories to the deal – voiced “great concern” at President Hassan Rouhani’s dramatic intervention.

“We strongly urge Iran to continue to implement its commitments under the JCPOA in full as it has done until now and to refrain from any escalatory steps,” they said in a joint statement, referring to the Joint Comprehensive Plan of Action.

“We reject any ultimatums and we will assess Iran’s compliance on the basis of Iran’s performance regarding its nuclear-related commitments under the JCPOA.”

The EU statement stressed the International Atomic Energy Agency’s (IAEA) role in monitoring Iran’s compliance with the deal – suggesting no concrete action is likely until the inspectors’ next report at the end of May.

But there are tensions within the EU, with some countries under domestic pressure to take a tougher line on Tehran, particularly after Iranian intelligence was accused over assassination plots in France, Denmark and the Netherlands.

Europe and Washington have been at loggerheads over how to deal with the Islamic republic since Trump took office. In recent days, the US deployed an aircraft carrier strike group to the Gulf – raising military tensions alongside the diplomatic discord.

EU scrabbling

Trump hit back at Tehran’s threats by tightening the economic screws further, slapping sanctions on the Iranian mining industry

The White House, which has already taken steps to scupper Iran’s oil exports said the steel and mining sector was the country’s second-largest source of foreign revenue, accounting for 10 per cent of exports.

“Tehran can expect further actions unless it fundamentally alters its conduct,” Trump said in a statement.

Since the US pullout, Europe has sought to keep Iran in the deal by trying to maintain trade via a special mechanism called Instex to clear payments without falling foul of US sanctions.

The European statement reiterated its commitment to helping the Iranian people enjoy the benefit of sanctions relief, condemning the US reimposition.

Europe is “determined to continue pursuing efforts to enable the continuation of legitimate trade with Iran” including through INSTEX.

But their efforts have borne little fruit so far, with Iran’s Supreme Leader Ayatollah Ali Khamenei dismissing them as a “bitter joke”.