French leader Emmanuel Macron on Tuesday urged his Iranian counterpart Hassan Rouhani to avoid an escalation of tensions after Washington blacklisted Iran's elite Revolutionary Guards as a terrorist organisation.
In a telephone conversation, Mr Macron urged Rouhani to "avoid any escalation or destabilisation of the region," the French presidency said in a statement.
President Donald Trump called the unit – which has some 125,000 troops and vast interests across the Iranian economy – Tehran's "primary means of directing and implementing its global terrorist campaign."
It was the first time that the United States has branded part of a foreign government a terrorist group, rather than guerrilla groups or other informal entities.
The move follows Trump's decision to pull the United States out of a multilateral deal with Iran that was meant to lift crippling economic sanctions in return curbs on Tehran's nuclear programme.
In response, Mr Rouhani on Tuesday accused the United States of being the real "leader of world terrorism".
The Revolutionary Guards are the ideological arm of Iran's military and deeply embedded in the country's political and economic life.
While the designation was welcomed in Israel, where Israeli Prime Minister Benjamin Netanyahu said he had asked for Washington to take the specific action.
"Thank you, my dear friend, US President Donald Trump," he said in a tweet. "Thank you for answering another of my important requests that serves the interests of our countries and of countries in the region."
Sen. Ted Cruz, R-Texas, called the action an "overdue" but essential step that should be followed by additional sanctions.
Rep. Michael McCaul of Texas, top Republican on the House Foreign Affairs Committee, said the designation "ends the facade that the IRGC is part of a normal military."
And, the Iranian opposition group, the National Council of Resistance of Iran, called it "an imperative for Middle East security, peace, and stability, and an urgent and necessary step to end war and terrorism throughout the region and the world."
But the move was rejected by close allies of Tehran. Turkey and Qatar raised objections to the decision.
“The United States issued this one-sided decision in the context of sanctions and pressure on Iran,” Turkish Foreign Minister Mevlut Cavusoglu said during a joint press conference with his Qatari counterpart Mohammed Bin Abdulrahman Al Thani.
“We do not support Iran’s Revolutionary Guards in Syria, but no country can declare another country’s armed forces a terrorist organisation. We also do not support unilateral decisions.” Such measures “would lead to instability in the region,” Mr Cavusoglu said.
In response to the decision, Iran declared the United States a "state sponsor of terrorism" and its forces in the region "terror groups".
Iran's top diplomat Mohammad Javad Zarif had earlier urged President Hassan Rouhani to place Centcom forces on Tehran's list of terror groups, his ministry said.
Mr Zarif blasted the US move on Twitter, saying it was timed to support Mr Netanyahu ahead of Tuesday's parliamentary election in the country that he looked set to win on Wednesday after initial results were released.
"A(nother) misguided election-eve gift to Netanyahu. A(nother) dangerous US misadventure in the region," he wrote.