According to Reuters, the diplomats said the decision was aimed at what they claimed to be a way to save the deal by discussing with Iran what it should do to reverse decisions it had made.
The aim was not to reimpose UN sanctions, the diplomats said.
Six European and Western diplomats said previously that Britain, France and Germany had agreed in principle to begin the process but they would still wait to see how significant Iran's steps were before taking a final decision, according to a report by Reuters.
The “dispute resolution mechanism,” is also known as the trigger mechanism and its activation can lead to the return of the UN sanctions against Iran.
The nuclear deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), was a deal struck between Iran and the five permanent UN Security Council members — the United States, Russia, China, France and the UK — as well as Germany and the European Union.
The treaty has come under increasing strain ever since President Donald Trump announced the US withdrawal from the deal in May 2018 and unleashed the “toughest ever” sanctions against Iran despite global criticism.
Earlier this week, the US president urged other signatories of the deal to pull out of what had remained of the JCPOA, promising to impose new economic sanctions on Tehran.
In response, Tehran has so far rowed back on its nuclear commitments five times, but stressed that it will reverse its measures as soon as Europe finds practical ways to shield mutual trade from the US sanctions.
MNA/PR