“It is in the interests of all to remain committed to the deal, but it is becoming increasing difficult,” Mogherini told reporters after a meeting of the parties at the United Nations on Wednesday.

She said France, Britain, Germany, Russia, China and Iran had agreed to continue efforts to implement the multilateral international deal, which US President Donald Trump left in May 2018.

The Trump administration also unleashed the “toughest ever” sanctions against the Islamic Republic following Washington’s withdrawal in defiance of global criticism in a bid to strangle the country’s oil trade.

Trump is a stern critic of the deal, which was clinched in 2015 by Iran and major world powers, including the United States, France, Britain, China, Russia, and Germany. Under the agreement, nuclear-related sanctions put in place against Iran were lifted in exchange for curbs on Tehran’s nuclear program.

In response to the US move to leave the JCPOA and reimpose sanctions, Tehran has so far rowed back on its nuclear commitments three times in compliance with articles 26 and 36 of the JCPOA, but stressed that its retaliatory measures will be reversible as soon as European signatories to the accord finds practical ways to shield the mutual trade from the US sanctions.

Iran says that if it does not receive economic benefits from the JCPOA by November it will further reduce its commitments.

“Every step that has been taken so far by Iran is reversible and we call on Iran to reverse these decisions and go back to full compliance,” Mogherini said, adding, “I hope that rationality will prevail.”

Trump’s goal has been to get another deal as he has already described the JCPOA as “the worst deal ever negotiated.” The White House position has been that maximum pressure will continue until Iranian officials accept to sit at the negotiating table.

Tehran says talks with Washington are impossible as the latter is pressing ahead with its hostile policy and refuses to lift sanctions against the Islamic Republic.

Iranian officials also say it was Washington that left the JCPOA last year although the deal was endorsed by the UN Security Council in the form of a resolution, stressing there will be no talks as long as the sanctions are in place.