Trump was asked Monday about two Saudi oil tankers and a Norwegian-flagged vessel being damaged in what Gulf officials described as a "sabotage" attack off the coast of the United Arab Emirates.
Details of the incident remain unclear. But it raised risks for shippers in a region vital to global energy supplies at a time of increasing tensions between the U.S. and Iran over its unraveling nuclear deal with world powers.
Trump was asked about the sabotage, and responded: "It's going to be a bad problem for Iran if something happens."
He spoke to reporters in the Oval Office while meeting with the prime minister of Hungary.