German Chancellor Angela Merkel and French President Nicolas Sarkozy have said Iran continues to pose a threat.
The leaders spoke days after a new US intelligence report was issued
The comments came as US Secretary of State Condoleezza Rice began talks with European and Russian officials in Brussels on Iran's nuclear programme.
A US intelligence report published on Monday said Iran had suspended a nuclear weapons programme in 2003.
But the report also said that Iran was continuing to enrich uranium, which can be used to make nuclear weapons.
Iran says the aims of its nuclear programme are peaceful.
"Iran continues to represent a threat," Mrs Merkel said during a joint news conference with Mr Sarkozy in Paris.
She did not specifically express support for a new UN sanctions resolution against Iran, which the US is calling for.
"We and our partners would like to continue with the UN process," Mrs Merkel said.
"I think we and our partners need to continue to seek dialogue with Iran," she said.
Mr Sarkozy said he agreed with his German counterpart that Iran still posed a danger, and that he supported the push for more sanctions.
"Notwithstanding the latest elements, everyone is fully conscious of the fact that there is a will of the Iranian leaders to obtain nuclear weapons.
"What made Iran move up to now, it was sanctions and firmness," he said.
The National Intelligence Estimate (NIE) released on Monday reversed earlier statements on Iran by the Bush administration.
Iranian President Mahmoud Ahmadinejad called the US report a "great victory" for Iran.
Ms Rice, who was in Brussels to urge more international pressure on the Iranians to halt uranium enrichment, said they still needed explain a covert programme up to 2003.
"I don't see that the NIE changes the course that we're on," Ms Rice said while travelling to Brussels, AP reported.