U.S. sanctions Iran's central bank -Trump
Trump outlined the action to reporters at the White House on Friday after first announcing his plan for further sanctions earlier this week on Twitter.
U.S. Treasury Secretary Steven Mnuchin, also speaking to reporters, said the bank was Tehran's last source of funds.
Asked about the possibility of a military response on Iran, Trump said the United States was always prepared and that a military strike was always a possibility.
Friday's action is the "highest level of sanctions," Trump said.
Iran has denied any involvement in the Sept. 14 attack, which shook global oil markets and ratcheted up tensions between Washington and Tehran. On Friday, Saudi officials took media to inspect the affected facilities. Saudi Arabia also blames the attacks on Iran.
Trump, who spoke to reporters at the White House alongside visiting Australian Prime Minister Scott Morrison, has said he wants a peaceful solution to the conflict following the weekend oil attacks. His secretary of state, Mike Pompeo, has called the attacks an "act of war."