President Trump said on Wednesday the Federal Aviation Administration would ground Boeing Co.’s fleet of 737 MAX airliners, after agency officials said new data indicated last weekend’s deadly crash in Ethiopia in some ways resembled another recent tragedy involving the same plane model.

Mr. Trump said the U.S. was stopping domestic airlines and others from using Boeing’s newest single-aisle plane in U.S. airspace. The order follows two high-profile crashes of 737 MAX planes within less than five months.

“The...