Iran's foreign minister said on Saturday that U.S. officials tried to discuss restarting nuclear talks last month, but he insisted Washington must first release $10 billion of Tehran's frozen funds as a sign of good will.
Iran has rejected direct talks with the United States, and indirect talks on reviving a 2015 nuclear accord aimed at keeping Iran from being able to develop a nuclear weapon stopped in June.
The United States used intermediaries at the United Nations last month to attempt to make contact, Foreign Minister Hossein Amirabdollahian told state television.
Iran has been unable to obtain tens of billions of dollars of its assets in foreign banks, mainly from exports of oil and gas, due to U.S. sanctions on its banking and energy sectors.