American businesses that have ventured into Cuba since former President Barack Obama moved to normalize relations with the country more than two years ago may see some of their progress thwarted by President Donald Trump's revision of Obama's policy.

Trump announced in Miami on Friday plans to tighten restrictions on American travel to Cuba and clamp down on U.S. business dealings with the Cuban military and intelligence security services. He has instructed the Treasury and Commerce Departments to begin writing new regulations on Cuba in a maneuver to reverse the efforts Obama took in late 2014 to ease the more than 50-year embargo against the island.

"A free Cuba is what we will soon achieve," he told a crowd of onlookers on Friday. "I keep my promises. Sometimes in politics they take a little bit longer... but we get there."

Trump's aim is to restrict the flow of money to oppressive elements of the Cuban regime and ensure that the statutory ban on tourism is strictly enforced. His policy reaffirms the U.S. statutory embargo on Cuba and opposes calls in the United Nations for its termination. It also mandates regular reporting on Cuba's progress.

Trump will not close embassies, break diplomatic relations or cut off commercial flights between the U.S. and Cuba, nor will he bring back the "wet foot, dry foot" policy toward Cuban immigrants eliminated by Obama in January.

The Treasury Department on Friday issued a Q&A on the changes.

Proponents of opening the U.S. to Cuba warned that Trump's overhaul will be a setback in an already slow-moving process and could harm American businesses that have entered the country under Obama. U.S. business have established 26 agreements with the Cuban government since 2015, according to ABC News.

"There are currently many different business sectors exploring options to expand their footprint in Cuba, and others have signed deals," said Alana Tummino, senior director of policy and head of the Cuba Working Group at the Americas Society and Council of the Americas (AS/COA).

"Cuba, even before the changes [under Trump]...was still one of the most highly complicated and sanctioned countries in the world from the United States, so businesses were already at a deep, deep disadvantage of entering into the Cuban market," said James Williams, president of Engage Cuba, a group that advocates for lifting the U.S. trade embargo. "Over the last two years, we've finally seen the fruits of those efforts starting to produce results."

Tourism companies have the most to lose from Trump's new Cuba policy, which will restrict self-directed travel and instead push American travelers into group trips that allow the U.S. government to ensure they are engaging in educational and cultural exchanges and not pure tourism. Group trips are more expensive than individual ones and will likely result in curbed travel.

A number of airlines have taken advantage of relaxed travel restrictions to Cuba under Obama, including American Airlines (AAL) , Delta Air Lines (DAL) , JetBlue (JBLU) , Southwest (LUV) and United Continental (UAL) . Cruise operators Royal Caribbean (RCL) , Carnival (CCL) and Norwegian Cruise Line (NCLH) have benefited as well.

To be sure, it has not been as fruitful as many had hoped. Some airlines that sought business in Cuba have since reversed course, including Frontier Airlines and Silver Airways, which dropped services entirely, according to Bloomberg.

Editors' pick: Originally published June 16.

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