"We call on Iran's leadership immediately to suspend its sensitive nuclear activities and abide fully by its international obligations," French President Nicolas Sarkozy, British Prime Minister David Cameron and German Chancellor Angela Merkel said in a joint statement.
"Our message is clear. We have no quarrel with the Iranian people. But the Iranian leadership has failed to restore international confidence in the exclusively peaceful nature of its nuclear programme," they said.
"We will not accept Iran acquiring a nuclear weapon. Iran has so far had no regard for its international obligations and is already exporting and threatening violence around its region."
The three leaders said "the door is open to Iran to engage in serious and meaningful negotiations about its nuclear programme.
"Until Iran comes to the table, we will be united behind strong measures to undermine the regime's ability to fund its nuclear programme, and to demonstrate the cost of a path that threatens the peace and security of us all."
The EU slapped an embargo on Iran's oil exports as part of the package of new sanctions Monday aimed at blocking funds for Tehran's suspect nuclear drive and pressing it to return to talks.
The oil ban, along with sanctions against Iran's central bank and other measures, come amid mounting concerns of confrontation after the UN atomic agency reported Tehran was inching ever closer to building a nuclear bomb.