MIAMI — President Trump announced a new policy toward Cuba on Friday that seeks to curb commercial dealings that benefit the Castro regime and could limit the freedom of some US citizens to travel to the island. But the policy leaves in place many changes implemented by his predecessor.

In a fiery speech delivered in the heart of Miami’s Little Havana, where an older generation of Cuban Americans has long objected to normalization of relations with the communist government of President Raúl Castro, Trump ticked off a list of examples, past and present, of the regimes’ repression of its citizens.

‘‘With God’s help, a free Cuba is what we will soon achieve,’’ Trump said at the Manuel Artime Theater, a highly symbolic venue named after a leader of the Bay of Pigs exile invasion of Cuba in 1961, a failed US-backed attempt to overthrow the revolutionary government of Fidel Castro.

Under the new policy, embassies in Havana and Washington will remain open. US airlines and cruise ships will still be allowed to serve the island 90 miles south of Florida.

Trump’s changes prohibit any commercial dealings with Cuba’s economically powerful military and, according to White House aides, was driven by the president’s concerns that the previous policy was enriching the Cuban military and intelligence services that contribute to repression on the island.

Through civilian-run holding companies, the Cuban military owns or controls much of the economy, particularly the tourism sector. Former president Barack Obama had allowed some transactions with the security services on grounds that money would trickle down to individual Cubans who gained employment and more contact with the outside world.

‘‘We now hold the cards. The previous administration’s easing of restrictions on travel and trade do not help the Cuban people,’’ Trump said. ‘‘They only enrich the Cuban regime.’’

Significantly, a new directive signed by Trump will not affect those elements of the normalization begun by Obama in December 2014 that are popular with younger Cuban Americans and others who have taken full advantage of them. Unlimited ‘‘family’’ travel and money sent to private Cubans on the island will remain unchanged.

Administration officials said no policy changes would go immediately into effect.

Instead, the new presidential directive will order the Treasury and Commerce departments to begin within 30 days to write new regulations that reverse some of those Obama implemented to ease the US embargo against Cuba that has remained in place for nearly 60 years. Only Congress can lift it.

Trump’s directive drew criticism outside the theater, including from the US Chamber of Commerce, which questioned the premise that the new restrictions would lead to reforms in Cuba.

‘‘US private-sector engagement can be a positive force for the kind of change we all wish to see in Cuba,’’ said Myron Brilliant, the group’s executive vice president and head of international affairs.

‘‘Unfortunately, today’s moves actually limit the possibility for positive change on the island and risk ceding growth opportunities to other countries that, frankly, may not share America’s interest in a free and democratic Cuba that respects human rights,’’ Brilliant said.

Trump cast his action as the fulfillment of a campaign promise.

‘‘Last year, I promised to be a voice against repression . . . and a voice for the freedom of the Cuban people,’’ he said. ‘‘You heard that pledge . . . and here I am.’’

A packed theater that included Cuban dissidents, dignitaries, and other guests gave Trump a raucous reception.

Among those who praised Trump ahead of his appearance were Carlos Lopez-Cantera, Florida’s first Cuban-American lieutenant governor, and Senator Marco Rubio, a Florida Republican, a one-time rival for the GOP presidential nomination who lobbied Trump hard to largely stick with a position he advocated during the campaign.

‘‘I want to express our deep gratitude to a man that’s really become a friend of mine,’’ Trump said of Rubio. ‘‘He’s one tough competitor.’’

Trump’s rhetoric in many cases outstripped the reality of what his order will accomplish.

Asked whether companies that have already signed Cuban contracts, such as Starwood Hotels and Resorts, should expect to lose money, an administration official said, ‘‘that will be handled in the specifics of regulations by Treasury and Commerce.’’