"I determine… that there is a sufficient supply of petroleum and petroleum products from countries other than Iran to permit a significant reduction in the volume of petroleum and petroleum products purchased from Iran by or through foreign financial institutions," Trump said in the memorandum on Friday.
The US president said he will continue to monitor the situation closely and has directed Secretary of State Mike Pompeo to publish this determination in the Federal Register.
The United States has ratcheted up sanctions on Iran since last year as part of its maximum pressure campaign, targeting the pillars of the Iranian economy.
In late September, the United States imposed another round of sanctions on Iran, including on the country’s central bank, after the attacks on the Saudi Aramco oil facilities.
The United States pins the blame on Iran for the attacks, but Tehran has repeatedly refuted the allegations of its involvement.