The United States on Friday announced new sanctions to curb Iran's oil exports, including targeting 14 vessels, moments after the adversaries wrapped up a day of indirect talks in Oman.
State Department spokesman Tommy Pigott said Iran uses oil revenue to "fund destabilising activities around the world and step up its repression inside Iran."
President Donald Trump is "committed to driving down the Iranian regime's illicit oil and petrochemical exports under the administration's maximum pressure campaign", Pigott said in a statement.
The State Department said it would order a block of any transactions with 14 vessels said to transport Iranian oil, including ships flagged from Turkey, India and the United Arab Emirates.
It also announced sanctions on 15 entities and two people and Trump signed an executive order that may impose a 25 percent tariff on countries that do business with Iran.
Since Trump's first administration, the United States has imposed sanctions to force all other countries to stop buying Iranian oil.
Iran's foreign minister met indirectly in Oman on Friday with senior Trump envoys on his country's nuclear program and said there was a "positive atmosphere."
The talks come after Iran's clerical state violently repressed some of the largest protests since the 1979 Iranian revolution.
Trump had threatened the use of force against Iran and ramped up the US military presence near Iran's shores.