Leaders of France, Germany and Britain, European signatories of Iran 2015 nuclear agreement, on Sunday said they are "extremely concerned" by the fuelling tension in the Gulf region, which they said likely to put the accord at risk unless the concerned parties join the same table of talks.

"Today, we are concerned about the risk that JCPoA (nuclear deal) will collapse following sanctions imposed by the United States and as a result of Iran's decision to no longer respect key provisions of the agreement," the three European countries (E3) said.

"The risks are such that it is necessary for all stakeholders to pause, and consider the possible consequences of their actions," they added in a statement released by the French President Emmanuel Macron's office.

"We believe that the time has come to act responsibly and to look for ways to stop the escalation of tension and resume dialogue," they stressed.

The three powers reiterated support of Iran nuclear accord, but they noted that its continuation depends on Tehran's full compliance with its obligations, urging Iran's officials to reverse activities aimed to boost nuclear enrichment beyond agreed parameters.

"Our countries have recently taken several diplomatic initiatives to contribute to de-escalation and to resume dialogue ... We will continue to explore the opportunities for talks to address the issue of Iran's compliance...," the statement said.

They also pledged to pursue "active engagement with all interested parties" to reach a solution able to preserve international peace and security.