British Foreign Secretary Jeremy Hunt is launching a fresh bid to stop the Iran nuclear deal unravelling and ease tensions in the Gulf.
Mr Hunt will meet EU foreign ministers in Brussels to raise concerns about Iran breaching some of its commitments.
The deal, which involves Iran limiting nuclear activities in return for the easing of economic sanctions, struggled after the US withdrew in 2018.
It comes amid heightened tensions after the UK seized an Iranian oil tanker.
On Saturday, Mr Hunt said the tanker, detained by Royal Marines earlier this month, could be released if the UK is guaranteed the oil it was carrying is not bound for Syria.
At a meeting of fellow foreign ministers on Monday, Mr Hunt will work with the European partners of the deal - France and Germany - to encourage Iran to stick to its pledges.
In a joint statement issued ahead of the meeting, Britain, France and Germany reiterated their support for the deal.
But said they were "deeply troubled" by recent events in the Gulf and "concerned" over US-Iran relations.
"We believe the time has come to act responsibly and seek a path to stop the escalation of tensions and resume dialogue," the statement said.
"The risks are such that it is necessary for all stakeholders to pause and consider the possible consequences of their actions."
Earlier this month Iran said it would be breaching the deal by breaking a limit set on uranium enrichment.
In 2018, Donald Trump said he would unilaterally withdraw the US from the agreement which was signed under the Barack Obama administration.
The other parties criticised Mr Trump's decision and said they remained committed to the deal.
On Sunday, the Mail on Sunday published a leaked memo which said Mr Trump abandoned the nuclear deal to spite Mr Obama.
Earlier this month, the International Atomic Energy Agency confirmed that Iran had breached the deal's cap on stockpiling of low-enriched uranium.
Iran said it was responding to sanctions reinstated by the US after Mr Trump abandoned the deal. Last week it confirmed it will break another of the limits imposed by the deal.
Deputy foreign minister Abbas Araqchi said Iran still wanted to salvage the deal but blamed European countries for failing to live up to their own commitments.