WASHINGTON—President Trump praised Mexico’s efforts to intercept Central American asylum seekers and said that Guatemala was getting ready to sign an agreement that would make it a final refuge for people fleeing poverty and violence in the region.

In a pair of tweets Monday night, Mr. Trump said that Guatemala was preparing to sign a “Safe-Third Agreement,” in an apparent reference to a legal designation that would require Central American migrants that cross into Guatemala to claim asylum there, blocking those migrants from lodging claims elsewhere.

Officials from Guatemala’s Foreign Ministry didn’t immediately respond to requests for comment, and the White House declined to immediately provide further details.

Mr. Trump also said Monday night that U.S. Immigration and Customs Enforcement would increase its efforts to remove people in the U.S. without authorization.

“Next week ICE will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States. They will be removed as fast as they come in,” wrote Mr. Trump.