Havana (AFP) - Cuba on Thursday rejected the latest US restrictions on travel to the island and stressed that its support for Venezuela's President Nicolas Maduro is "not negotiable."

The official statement was published by the Cuban press two days after the US Treasury Department banned group educational travel as well as cruise ship and private yacht visits by Americans to Cuba, linking the action to Havana's backing of Maduro.

"Cuba's solidarity with the constitutional President Nicolas Maduro Moros, the Bolivarian and Chavista Revolution and the civil-military union of its people, is not negotiable," it said.

The last US cruise ship sailed out of Havana's harbor on Wednesday as the US ban went into effect, targeting a burgeoning tourism market that had seen visits by more than 250,000 Americans in the first quarter of 2019.

"We will continue to take actions to restrict the Cuban regime's access to US dollars," US National Security Advisor John Bolton said.

Among the reasons given by the US State Department for the latest action was Cuba's "interference in Venezuela, and its direct role in the man-made crisis led by Nicolas Maduro."

The Cuban statement charged that Washington had come up with "new pretexts" for its attacks.

"The most notorious is the slanderous accusation that Cuba intervenes militarily in Venezuela, a lie that has been publicly and consistently rejected by the Cuban government."

Washington's aim was "to tear back political concessions made to the Cuban nation, by asphyxiating the economy and causing harm to the population."

"They won't be able to asphyxiate us, nor stop us," the statement said.

Venezuela has been Cuba's top ally for nearly two decades, and also its main supplier of oil.

Washington has called for Maduro to step down in favor of US-backed opposition leader Juan Guaido, and has demanded that Havana withdraw Cuban military personnel that it says are keeping the Venezuelan president in power.

Cuba has 20,000 civilian personnel in Venezuela, mainly doctors, but denies it has military personnel on the ground there.

Since coming to office in 2017, US President Donald Trump has dismantled the rapprochement with Havana begun by former US president Barack Obama.