With the causes of the delay unknown, Javier Solana and Ali Larijani are likely to meet next week, media said.
Solana and Larijani were expected to discuss a package of incentives drafted by five permanent UN Security Council members and Germany in a bid to persuade Iran to suspend work on enriching uranium, which the countries fear could be used in weapons production. Tehran though insists in needs nuclear fuel for generating electricity.
Hamid Reza Asefi, Iranian Foreign Ministry official spokesman, said earlier Solana and Larijani were to clarify issues in the package that Tehran found ambiguous.
Details of the proposals remain confidential at the moment in line with a request from Iran, which said it did not want pressure while studying and discussing them.
But Russian Foreign Minister Sergei Lavrov said the proposals put forward by Russia, the United States, China, the United Kingdom, Germany, and France embraced Iran's nuclear program, economic and trade cooperation with the Islamic Republic, and security guarantees.
On Tuesday, Russian President Vladimir Putin urged Tehran to respond to the proposals, whereas the United States earlier said it wanted a response by July 12.
