Russian Foreign Minister Sergei Lavrov said on Tuesday that US sanctions on Iran were not legitimate, in Moscow's first official comment since Washington restored sanctions on Tehran.
Lavrov said Moscow, itself a target of separate US sanctions, expected there would be ways to pursue economic cooperation with Iran despite the reimposition of sanctions on Monday on the country's oil, banking and transport sectors.
Speaking in Madrid, Lavrov said Washington had used "unacceptable methods" to pressure operators of the SWIFT global financial network into cutting off Iranian banks.
Russia and its European partners were looking for ways to maintain economic ties with Tehran, he said after meeting his Spanish counterpart Josep Borrell, but provided no details.
Tehran said on Tuesday it had so far been able to sell as much oil as it needs despite US pressure, but urged European countries that oppose the sanctions to do more to shield Iran.