"I would like to see a large cut and I'd like to see immediately the quantitative tightening stop," Trump told reporters outside the White House.
"I'm very disappointed in the Fed. I think they acted too quickly by far, and I think I've been proven right ... The Fed is often wrong," Trump added.
Trump made the comments as the Fed began its two-day policy meeting.
Fed Chairman Jerome Powell signaled earlier this month that the central bank would ease monetary policy as the US economy faces headwinds from weak global growth, trade tensions and Britain's possible disorderly departure from the European Union.