(CNN) The US announced major new restrictions on US citizens traveling to Cuba on Tuesday, blocking the most common way Americans are able to visit the island -- through organized tour groups that license US citizens to travel automatically -- and banning US cruise ships from stopping in the country.

American tourism is not explicitly permitted in Cuba. However, Americans can travel to Cuba if it is covered under specific categories, which included organized group travel, known as group people-to-people travel, until Tuesday.

Treasury Secretary Steven Mnuchin said in the statement that the restrictions are a result of Cuba continuing "to play a destabilizing role in the Western Hemisphere, providing a communist foothold in the region and propping up US adversaries in places like Venezuela and Nicaragua by fomenting instability, undermining the rule of law, and suppressing democratic processes."

The State Department announced that "going forward, the United States will prohibit US travelers from going to Cuba under the previous 'group people-to-people educational' travel authorization. In addition, the United States will no longer permit visits to Cuba via passenger and recreational vessels, including cruise ships and yachts, and private and corporate aircraft."

A State Department spokesperson for Western Hemisphere affairs said the new restrictions "on US passenger and recreational vessels, including cruise ships and yachts, and corporate and private aircraft, steers American dollars away from the Cuban regime, and its military and security services, who control the tourism industry in Cuba."

Commercial flights from the US will continue to be permitted as they "broadly support family travel and other lawful forms of travel," according to the spokesperson.

The Trump administration announced plans to further restrict travel to Cuba in April, when White House national security adviser John Bolton said the Treasury Department would "implement further regulatory changes to restrict non-family travel to Cuba."

Garrett Marquis, a spokesman for the White House National Security Council, said the new restrictions are part of President Donald Trump's commitment to holding "the Cuban regime accountable for its direct destabilizing role in the hemisphere and contribution to the repression of the people of Venezuela."

Commerce Secretary Wilbur Ross maintained that "Cuba remains communist, and the United States, under the previous administration, made too many concessions to one of our historically most aggressive adversaries."

Under President Barack Obama, the US eased several restrictions with Cuba, permitting, among other things, educational tours, commercial air travel and cruises of the island for American citizens. The US also reopened its embassy in Havana and Cuba reopened its embassy in Washington.

Cuban Minister of Foreign Affairs Bruno Rodríguez Parrilla, who reopened the Cuban embassy in Washington in 2015, called the new restrictions "an attack on international law."

"The tightening of the US blockade against Cuba and its extraterritorial implementation is and the sovereignty of all States. It is the main obstacle to our development and a flagrant violation of the human rights of all Cubans," Rodríguez Parilla said in a tweet.

Engage Cuba, a group which works to foster business between the US and Cuba, called the restrictions "an attack on our fundamental right as citizens."

"The federal government should not be policing where Americans go on vacation. Our core freedoms should not be held hostage by politicians for naked partisanship," said James Williams, president of Engage Cuba. "Today's news is especially damaging for the Cuban people, particularly the burgeoning Cuban private sector, who rely on American travelers to support their businesses and families."

Cuban government statistics say US citizens have quickly grown to become the second largest foreign group visiting the island after Canadians.

The Treasury Department in a statement clarified that "certain group people-to-people educational travel that previously was authorized will continue to be authorized where the traveler had already completed at least one travel-related transaction (such as purchasing a flight or reserving accommodation) prior to June 5, 2019."

The Trump administration recently allowed US companies and Cuban-Americans to sue companies using property that was seized after the 1959 Cuban revolution, including cruise ship terminals and airports.

Carnival Cruise Line was the first company to be sued under the law, Title III of the Helms-Burton Act, which previous administrations had waived.