Iran's Fars news agency had reported earlier in the day that Tehran's written response to the five permanent UN Security Council members and Germany had been handed to EU officials.
"The document handed to High Representative for the Common Foreign and Security Policy Javier Solana is a verbatim of yesterday's phone conversation between Solana and Iranian Supreme National Security Council Secretary Saeed Jalili," the source said.
"The document is not Tehran's response to the six countries' proposals, as earlier reported by some media," the source said.
Iran's top nuclear negotiator and the European Union's foreign policy supremo discussed Iran's nuclear program over the telephone Monday.
A senior Iranian Foreign Ministry official said ahead of the conversation between Saeed Jalili and Javier Solana that Tehran would not yield to international demands and back down on its right for civilian nuclear technology.
Iran failed to give a response Saturday - an informal deadline set by the six nations involved in the long-running nuclear talks - to proposals designed to persuade Tehran to suspend its uranium enrichment, a process that can be used in nuclear weapons production.
The United States said Iran would now inevitably face tougher sanctions. Tehran brushed aside the warning.
At talks in Geneva on July 19, the six nations put forward a package of trade and nuclear technology incentives to Tehran, demanding a response within two weeks.
Iran's Islamic Revolution Guards Corps Commander Mohammad Ali Jafari reiterated a threat in comments quoted by Fars news agency on Monday to block the Strait of Hormuz, through which about 40% of global oil shipments pass, in the event of aggression against the country.
The U.S. and Israel have refused to rule out military action against Iran, the world's fourth largest oil producer, if diplomacy fails to end the dispute.
Iran recently conducted a series of missile test launches in the strait, which is located at the southern end of the Persian Gulf.
A Russian Foreign Ministry spokesman said Tuesday deputy foreign ministers of the Iran Six could hold a phone conference on Wednesday to discuss the situation.
