But the United States has refused to join an initiative by the EU, represented by France, Germany and Britain, to offer Iran incentives to curtail its nuclear programme.
"I believe the European countries have eventually understood that Iran's nuclear capability is not for sale," said Sirus Naseri, a senior member of Iran's negotiating team currently engaged in talks about the nuclear issue with the EU.
"The final agreement in these negotiations will be based on the continuation of (uranium) enrichment by Iran," Naseri told the official IRNA news agency in Vienna.
"We will give the Europeans an opportunity to reach this stance but this opportunity won't be permanent," he added.