U.S. Secretary of State Hillary Clinton said India, Malaysia, South Korea, South Africa, Sri Lanka, Taiwan and Turkey reduced the amount of crude oil purchased from Iran.
That meant that U.S. sanctions targeting the Iranian energy sector "will not apply to their financial institutions for a potentially renewable period of 180 days," she said in a statement.
Belgium, the Czech Republic, France, Germany, Greece, Italy, Japan, the Netherlands, Poland, Spain and the United Kingdom made similar moves this year.
The European Union in January banned new purchases of Iranian crude oil and agreed to phase out existing contracts by July. Tehran pre-empted the EU move by banning exports to some EU members, though some of the countries had already halted Iranian crude oil purchases.
"By reducing Iran's oil sales, we are sending a decisive message to Iran's leaders: until they take concrete actions to satisfy the concerns of the international community, they will continue to face increasing isolation and pressure," said Clinton.
Washington and its allies say Iran is using oil and natural gas revenues to finance a nuclear program believed to be geared toward a weapon. Tehran maintains its intentions are peaceful and has met with international negotiators to allay concerns.