The central bank’s study, which comes as Europe and the United States prepare to begin high-level trade talks, reinforces other research showing that the tariffs on European goods have, by themselves, not amounted to very much. They have probably hurt the United States economy more than the intended targets.

One reason is that much of the steel that Europeans sell to the United States is specially formulated for specific uses, like aircraft parts or oil drilling equipment. American companies cannot find domestic suppliers able to provide the same products, which often contain patented combinations of minerals or other metals. So they simply wind up paying the tariffs of 10 percent on aluminum and 25 percent on steel and passing the extra cost on to American consumers.

“There was not necessarily a lot of production capacity in the U.S. to pick up the slack,” said Oliver Rakau, chief German economist at Oxford Economics, who was not involved in the central bank study.

At the same time, the trade war is having a significant psychological impact. Mr. Trump has rattled European confidence with the tariffs and his threats to expand the levies to include cars. Fearful of what may come next, businesspeople are delaying plans to expand their factories or hire new workers.