“This is not a decision by our Fathom brand, but rather a Cuba decision,” Roger Frizzell, chief communications officer for Carnival Corporation, wrote in an email. “Cuba allows Cuban-born individuals to enter the country by airplanes, but not by ships yet.”

He said the company has requested a change in the regulation and is working on the issue.

The Movimiento Democracia, a human rights organization that organized Tuesday’s protest, announced on its Facebook page that: “this is not against the cruise ships traveling to Cuba. We believe that building bridges with free people will help build freedom to the oppressed Cuban people. This is against the apartheid by virtue [of] nationality policy that offends human rights and human dignity.”

The organization plans a flotilla to follow the Adonia on May 1 to Cuba in protest.

The French cruise line Ponant also recently received permission to take Americans on cruises around Cuba. Its itineraries, set to begin in January 2017, require travelers to fly to the island to board the 64-passenger ship. Cuban-born travelers would presumably be prevented from taking those cruises as well.

A representative for Ponant wrote in an email that “the company will be in full compliance to any special requirements or regulations set by the U.S. or Cuban government.”