While Mr. Trump said during the Republican primary race that restoring diplomatic relations with Cuba — a step the Obama administration took last summer — was “fine,” he called Mr. Obama’s December 2014 agreement with President Raúl Castro of Cuba, Mr. Castro’s younger brother, a “very weak agreement” that provided too many “concessions” to the Cubans.

“All of the concessions Barack Obama has granted the Castro regime were done through executive order, which means the next president can reverse them, and that I will do unless the Castro regime meets our demands,” Mr. Trump said at a campaign event in Miami in September. “Not my demands. Our demands.”

Mr. Trump announced last week that he had named Mauricio Claver-Carone, a fierce critic of Mr. Obama’s opening with Cuba who leads a pro-embargo political action committee, to his transition team for the Treasury Department. The move was seen as a signal that Mr. Trump is considering unraveling the web of regulations Mr. Obama has put in place to ease trade and commercial restrictions against Cuba.

Last month, Mr. Obama issued a sweeping directive setting forth a new United States policy to lift the Cold War trade embargo entirely — a move that would require congressional approval — and end a half-century of clandestine plotting against Cuba’s government. And he announced that his administration was lifting perhaps the most symbolically potent aspect of trade restrictions, the $100 limit on bringing Cuban rum and cigars into the United States. Earlier, Mr. Obama had also resumed direct flights between the two countries.

“During my presidency, we have worked hard to put the past behind us, pursuing a future in which the relationship between our two countries is defined not by our differences but by the many things that we share as neighbors and friends — bonds of family, culture, commerce and common humanity,” Mr. Obama said in his statement.

Advocates of the opening argued that Mr. Castro’s death could be a pivot point, clearing away the last emotionally charged remnants of a policy that has outlived its usefulness.