The UK, France and Germany said on Friday they would not back U.S. efforts to unilaterally trigger the reimposition of United Nations sanctions on Iran, but said they wanted talks with Tehran over its ongoing violations of a 2015 nuclear accord.

Under Iran's 2015 deal with world powers to accept limits to its nuclear program in return for the lifting of sanctions, a UN weapons embargo is due to expire in October. The U.S., which exited the deal in 2018, says it wants to extend the embargo.

If the UN Security Council does not extend the embargo, Washington has threatened to trigger a so-called "snapback" of all UN sanctions on Iran, using a process outlined in the nuclear deal.

Such a move would likely kill the nuclear accord.

"We firmly believe that any unilateral attempt to trigger UN sanctions snapback would have serious adverse consequences in the UN Security Council," the foreign ministers of the three European countries (E3) said in a statement.

"We would not support such a decision, which would be incompatible with our current efforts to preserve the JCPoA [Iran nuclear deal]," they said, after discussing the Iran situation in Berlin.

European diplomats are working on a compromise, but it is unclear whether they will be able to satisfy the U.S. as well as Russia and China, which like the E3 remain committed to the deal.

"We believe that the planned lifting of the UN conventional arms embargo ... would have major implications for regional security and stability," the E3 said, adding it was working in coordination with China and Russia on the issue.

Speaking to reporters on Friday in a teleconference call, the U.S. special envoy to Iran, Brian Hook, declined to comment on a potential compromise.

"Nobody can argue that Iran's behavior since 2015 merits a lifting of the arms embargo," he said.

The E3 ministers said they hoped to hold a ministerial meeting with Iran to discuss its violations of the nuclear deal and assess a mechanism they had launched in January aimed at resolving differences within its framework.

"We remain committed to the JCPoA and, in order to preserve it, urge Iran to reverse all measures inconsistent with the agreement and return to full compliance without delay," they said.