European Union foreign policy chief Javier Solana said he planned to respond to the letter to after consulting with other leaders, CNN reported Monday.
"We have not responded yet. We are still talking among ourselves," Solana said at an EU-NATO meeting in Paris. "But I hope we'll have a response soon."
Last month, world powers offered economic and other incentives if Iran suspended its uranium enrichment program.
On Friday, the Islamic republic replied to the proposal hammered out by the foreign ministers of the permanent members of the United Nations Security Council -- the United States, Britain, China, Russia and France; Germany, which has been involved in nuclear talks; and Solana.
As for meeting with top Iranian nuclear negotiator Saeed Jalili, Solana said such a meeting "is not impossible" for now.