Philippe Douste-Blazy, the French foreign minister, also said discussion of sanctions should await the IAEA report.
"We're not there yet - let's wait for April 28," he told French radio, adding that use of military force against Iran was "absolutely not a question today".
All options open
Tuesday's meeting was called after Tehran declared last week that it had enriched uranium and was aiming for industrial-scale production.
Germany said on Wednesday that Angela Merkel, the German leader, and Vladimir Putin, the Russian president, would discuss Iran's nuclear plans during a meeting in the western Siberian city of Tomsk next week.
Jack Straw, the UK foreign secretary, told the BBC that the British government was working on the assumption that Iran would not meet the proposals.
"What is most likely to happen is that the matter will move back to the Security Council and there will then be discussions about the next steps," he said.
"All options are on the table"
Meanwhile, George Bush, the US president, also said he would discuss Iran's nuclear activities with Hu Jintao, China's president. Hu has been cool towards sanctions.
Asked if his options included planning for a nuclear strike, Bush said: "All options are on the table."
However, he added that the US still wished to solve the issue through diplomatic means.
Washington believes Iran is trying to build bombs, but Tehran says it is only developing nuclear energy and will continue doing so.
The US, which already enforces its own sanctions on Iran, wants the UN Security Council to be ready for diplomatic action, including measures such as a freeze on assets and visa curbs on Iranian officials.