U.S. President Donald Trump is keeping all options on the table for responding to Iran's unrest, White House Press Secretary Karoline Leavitt said Thursday.

"The president and his team are closely monitoring this situation, and all options remain on the table for the president," she said at a press briefing, warning of "grave consequences" if the killing continues in Iran.

Citing a senior U.S. official, The New York Times reported Thursday that Israeli Prime Minister Benjamin Netanyahu spoke to Trump on Wednesday, asking the White House to postpone any U.S. military attack on Iran, which Trump reportedly has been weighing for days.

The U.S. military is evacuating troops from Middle East bases and sending reinforcements to the region, according to a report by U.S. media outlet Axios.

On Thursday, the U.S. Department of the Treasury announced sanctions on more than 20 individuals and entities allegedly related to Iran.

Protests have been held since late December in several Iranian cities. Authorities said they are prepared to address economic grievances, while warning against violence, vandalism and unrest.

Initially peaceful, the protests gradually escalated into violence, resulting in casualties and damage to public property, including mosques, government buildings and banks. Iranian authorities have attributed the unrest to interference by the United States and Israel.