Britain, France and Germany try persuade Iran to stop all activities that might be used to make a nuclear bomb. Instead, they proposed Iran economic and political cooperation Friday.
Ambassadors of the three countries involved in the negotiations - the UK, France and Germany - are reported to have proposed certain incentives.
Reuters quoted an Iranian official as saying the E.U. offered to support it as the main transit route for oil and gas to Europe from Central Asia.
Iran has threatened to resume its uranium enrichment programme, BBC reminds.
France, Germany and the UK have said this would end two years of talks on Iran's nuclear activities.
After the proposal was put to Iran on Friday, French Foreign Minister Philippe Douste-Blazy said he thought the undisclosed proposals were "ambitious and generous".
Iran says it aims only to generate electricity and has a right to a peaceful nuclear programme that includes processing its own nuclear fuel.
"Even if their proposals do not allow the resumption of work at Isfahan, we will resume activities," Hossein Mousavian, a senior nuclear negotiator, told Reuters.
Another Iranian source close to the talks said the trio had offered to allow Western companies to build nuclear power stations in Iran and supply fuel for them.
Iran says it needs nuclear power stations to meet booming electricity demand. The E.U. offer of power stations could help it to meet that demand without having to process its own nuclear fuel - which could be used to make a bomb.