WASHINGTON - U.S. President Donald Trump announced new sanctions against Iran's national bank Friday, further escalating economic pressure on the Islamic Republic.

"I think the sanctions work," Trump said during a joint White House news conference with Australian Prime Minister Scott Morrison. Trump also said "the military would work, but that is a very severe form of winning."

The sanctions came after last weekend's attacks on Saudi Arabian oil installations that U.S. officials said were carried out by Iran, an allegation that Tehran denies.

But Trump said he was not planning a military response to the attacks, telling reporters in the Oval Office, "the strong person approach and the thing that does show strength would be showing a little bit of restraint."

Trump warned, however, that "Iran knows if they misbehave, they're on borrowed time."

Trump announced the sanctions as his administration weighs options on Iran, including actions to further weaken its economy, deploying more U.S. troops to the Middle East region and targeted military strikes.

Iranian Foreign Minister Mohammad Javad Zarif said on Thursday a U.S. or Saudi Arabian military strike against his country would trigger "an all-out war."

The United States previously imposed sweeping sanctions on Iran because of its alleged nuclear program. But the U.S. Treasury Department said Friday the latest sanctions were imposed because Iran's central bank engaged in "terrorism" by providing "billions of dollars" to the Islamic Revolutionary Guards Corps and Hezbollah.

Iranian President Hassan Rouhani has often said that any negotiations between himself and Trump can only occur if the U.S. first provides sanctions relief.