Russia’s Foreign Ministry said in a statement: “We do not rule out the possibility that the Europeans’ ill-considered actions could lead to further escalation.”
The ministry added the “deeply disappointing” decision could make it “impossible” to resume implementation of the accord.
France, Britain and Germany confirmed earlier on Tuesday they had triggered the dispute mechanism given Tehran’s ongoing violations, but said they were not joining the “maximum pressure” campaign by US President Donald Trump’s administration, which quit the pact in 2018 and has re-imposed tough economic sanctions on Iran.
The three countries said in a joint statement: “We do not accept the argument that Iran is entitled to reduce compliance with the deal.”
The nations claimed they had no choice but to launch the process that could eventually lead to UN sanctions.
They added: “We do this in good faith with the overarching objective of preserving the deal and in the sincere hope of finding a way forward to resolve the impasse … while preserving the agreement and remaining within its framework.”
The European powers said they had taken the step to avoid adding “a nuclear proliferation crisis to the current escalation threatening the whole region”.
Under the mechanism, the EU states should inform the other parties to the deal – Russia and China as well as Iran. They then have 15 days to resolve differences, a deadline that can be extended or ultimately lead to fresh sanctions.
Iran, which denies Western claims its nuclear programme is aimed at building a bomb, has gradually rolled back its commitments under the accord since the US’ shock exit.
It took yet another step away from the treaty by announcing on January 6 that it would scrap limits on enriching uranium.
Tehran argues that Washington’s actions justify its breaches, and has repeatedly accused the deal’s European signatories of failing to shield its economy from crippling US penalties.
Mr Trump, for his part, has argued that the deal signed by his predecessor Barack Obama was too weak and that new sanctions would force Iran to accept more stringent terms. Iran refuses to negotiate with sanctions in place.
Iran’s Foreign Minister Javad Zarif slammed the EU’s move to trigger the dispute mechanism as a “strategic mistake,” while insisting that the deal to curb its nuclear activities “is not dead”.
“No, it’s not dead. It’s not dead,” he told Reuters on the sidelines of an event in New Delhi on Wednesday.
The nuclear diplomacy is at the heart of wider confrontation between Tehran and Washington, which have teetered on the brink of war ever since a US air strike killed Iran’s top military commander in Baghdad earlier this month.
Iran responded to General Qassem Soleimani’s death by launching missiles at US targets in Iraq.