Mr. Trump, in a series of tweets, accused Mr. Draghi of deliberately pushing down the value of the euro “making it unfairly easier for them to compete against the USA.”

“They have been getting away with this for years, along with China and others,” he tweeted.

Speaking to reporters at the White House later in the day, Mr. Trump said Mr. Draghi “did something today that was very dramatic. And, frankly, it helped that part of the world.”

Mr. Trump is viewing international economic policies through an increasingly narrow lens, observing only how decisions will affect the United States and seeing other countries’ attempts to help their economies as working against America’s interests. He has continually accused the Federal Reserve of putting the United States at a disadvantage to China, Europe and others by raising interest rates and has urged the central bank to take steps to strengthen the American economy, including cutting rates and restarting crisis-era stimulus programs.

On Tuesday afternoon, Mr. Trump suggested that he would consider demoting the Fed’s chairman, Jerome H. Powell, if the United States central bank did not also move toward easing policy. The Fed is expected to leave rates unchanged on Wednesday after a two-day policy meeting. But many economists expect Fed officials to signal that they are willing to cut rates soon if a slowing global economy and escalating trade tensions threaten the outlook for United States growth.

“We’ll see what happens; they’re going to be making an announcement pretty soon, so we’ll see what happens,” Mr. Trump said, when asked whether he would take the unprecedented step of trying to strip Mr. Powell of his chairmanship. “I want to be given a level playing field, and so far I haven’t been.”