UN Secretary General Antonio Guterres says that Iran's nuclear agreement, known as the Joint Comprehensive Plan of Action (JCPOA), must be preserved.
On Wednesday, UN spokesman Stephane Dujarric said Guterres believes that the JCPOA is "very important and it should be maintained."
"We must build on this important achievement to preserve the non-proliferation regime which is a cornerstone of our global security," he added.
The UN chief met with Iran's Foreign Minister Mohammad Javad Zarif in New York on Tuesday to discuss the deal.
During an interview with The Associated Press on Tuesday, Zarif said Iran will “mostly likely” abandon the 2015 nuclear deal should the United States choose to withdraw from the multilateral agreement.
“If the United States were to withdraw from the nuclear deal, the immediate consequence in all likelihood would be that Iran would reciprocate and withdraw,” Zarif said. “There won’t be any deal for Iran to stay in.”
Saving Iran agreement Germany's highest priority
Meanwhile, a German Foreign Ministry spokesman, Rainer Breul, said that Germany does not reject a supplementary deal but rejected changing the JCPOA.
“For us... the highest priority is keeping the nuclear agreement and full implementation on all sides,” he said.
“The nuclear agreement was negotiated with seven countries and the EU and can’t be renegotiated or replaced on a whim,” he added.
Earlier in the day, French President Emmanuel Macron said his country will not leave the deal.
"We should not abandon it without having something substantial and more substantial instead. That's why France will not leave the JCPOA, because we signed it," he said.
US President Donald Trump has often vowed to pull the United States out of the 2015 nuclear pact between Iran and the P5+1 group of countries, which was negotiated under his predecessor, Barack Obama.
Back in January, Trump said it was the last time he was extending the sanctions relief for Iran as part of the nuclear agreement, giving the European signatories a May 12 deadline to fix what he claimed to be the “flaws” in the agreement or he would refuse to waive those bans.
Iran has repeatedly warned that any failure to respect the multinational agreement would have grave consequences, stressing that there is no alternative to the nuclear accord.