President Donald Trump said Wednesday he ordered the Treasury Department to "substantially increase" sanctions on Iran.
Trump's announcement follows strikes Saturday on the world's largest crude-processing plant and oil field in Saudi Arabia. The U.S. accused Iran of carrying out the attacks.
It was not immediately clear what steps the president directed Treasury Secretary Steven Mnuchin to take. Asked about the sanctions later Wednesday during stops in California, the president told reporters he would announce details over the next 48 hours. The Treasury Department, White House and State Department did not immediately respond to CNBC's requests to comment.
The strikes triggered the largest spike in crude prices in decades and renewed concerns of a budding conflict in the Middle East. All the while, Iran maintains that it was not behind the attacks.
U.S. crude and benchmark global Brent oil prices dropped Wednesday after the White House announced sanctions instead of military action.
On Tuesday, Trump said aboard Air Force One that he does not intend to meet with Iranian President Hassan Rouhani at the U.N. General Assembly in New York next week.
"I'm not looking to meet him. I don't think they're ready yet, but I'd prefer not meeting him," Trump said. Rouhani likewise said he would not meet with Trump.
The foreign ministry of Russia, a key strategic ally to Iran, called Trump's plan destructive and said it would not solve anything, Reuters reported, citing news agency Interfax.
On Sunday, Trump warned that the United States was "locked and loaded" to respond to the attack on the Saudis, but a day later, he dialed down his rhetoric, saying there was "no rush" to take action and that the U.S. was coordinating with allies.
Secretary of Defense Mark Esper also spoke with Saudi Crown Prince Mohammed bin Salman on Monday. Secretary of State Mike Pompeo traveled to the kingdom Tuesday.
The Pentagon's top Air Force general said Tuesday that while the service had not yet received direction to send additional bomber aircraft to the region, the U.S. was closely monitoring the area.
The latest confrontation represents another brick in the crumbling edifice between Washington and Tehran after a string of attacks in the Persian Gulf in recent months.
In June, U.S. officials said an Iranian surface-to-air missile shot down an American military surveillance drone over the Strait of Hormuz. Iran said the aircraft was over its territory.
Hours later, Trump said Iran made a "very big mistake" by shooting down the spy drone. The downing came a week after the U.S. blamed Iran for attacks on two oil tankers in the Persian Gulf region and after four tankers were attacked in May.
The U.S. in June slapped new sanctions on Iranian military leaders blamed for shooting down the drone. The measures also aimed to block financial resources for Iran's Supreme Leader Ayatollah Ali Khamenei.
Though Trump has threatened to bring military action or even "fire and fury" against American adversaries, he has also said he does not want to throw the U.S. into another prolonged military conflict. In a tweet Tuesday, Trump called his measured response to the strikes "a sign of strength that some people just don't understand!"
U.S. congressional leaders from both major parties had urged Trump to respond to the strikes.