German Foreign Minister Heiko Maas has criticized Washington’s re-imposition of sanctions against Tehran, pledging to work to guarantee the survival of the Iran nuclear agreement abandoned by the US in defiance of opposition from other parties to the deal.

The top diplomat said in an interview with German newspaper Passauer Neue Presse on Wednesday that US President Donald Trump’s decision to re-impose sanctions on Iran in contravention of the deal was a “mistake.”

“We still consider it a mistake to pull out of the nuclear agreement with Iran,” Maas added.

The agreement with Iran was signed in 2015 by the five permanent members of the UN Security Council, including the US, plus Germany under then US president Barack Obama.

Under the deal, known as the Joint Comprehensive Plan of Action (JCPOA), Iran undertook to put limits on its nuclear program in exchange for the removal of nuclear-related sanctions imposed against Tehran.

Trump pulled the US out of the Iran nuclear agreement in May, and said that he plans to reinstate US nuclear sanctions on Iran and impose "the highest level" of economic bans on the Islamic Republic.

On Monday, Trump signed an executive order re-imposing sanctions on Iran to levy "maximum economic pressure" on the Islamic Republic.

Maas said in his interview that Germany and the EU would fight to keep the deal alive, even without the US.

“We will fight for it because it is in our interest in terms of security that there is security and transparency in the (Middle East),” he said.

The US withdrawal from the deal and its re-imposition of sanctions come as other signatories to the agreement have pledged to protest the JCPOA.

The European Union has said the international community has an obligation to maintain economic relations with Iran.

EU foreign policy chief Federica Mogherini said during a trip to Wellington, New Zealand, on Tuesday that Iran was in compliance with its obligations under the agreement, which warranted reciprocal commitment.

“So the deal has two parts: Iran gives up their nuclear program and the international community opens up trade and economic relations with Iran. This second pillar has to be maintained if we want the first pillar to be maintained,” Mogherini said. “So far, Iran has been compliant fully with their nuclear commitments.”

Russia and China, the non-EU parties to the deal, have also repudiated new US sanctions on Iran, pledging to maintain trade ties with Tehran.

UN expresses 'continued support' for JCPOA

Meanwhile, a spokesman for UN Secretary General Antonio Guterres also threw the world body’s weight behind the landmark deal.

"The secretary general has, himself, repeatedly discussed the importance of the Joint Comprehensive Plan of Action as one of the key diplomatic achievements of recent years. He believes that it deserves continued support and that all of the parties to that agreement need to abide by its terms," Farhan Haq said early on Wednesday.

"There was an agreement (the JCPOA) put into place and the secretary general's views on that agreement are well known. We will continue as far as we can to support implementation of the JCPOA, which as you know also involves the activity of the International Atomic Energy Agency (IAEA),” he added.