The fortresses and cobbled streets of the ancient Croatian town of Dubrovnik are often crowded with tourists eager to visit the locations from the Game of Thrones television series or the Star Wars: The Last Jedi film, Reuters reports.

But comments by United States President Donald Trump this month that he will impose a 100% tariff on all movies produced outside the United States have alarmed the entertainment industry and some locals in Dubrovnik who fear directors may no longer film there.

"There have been huge disruptions because of the tariffs that Trump plans to introduce," said Croatian film producer Igor Aleksandar Nola, adding that budgets had already been hit by global economic upheaval.

"Part of the financing coming from banks and investment funds for audio-visual arts has been on standby because of the uncertainty," Nola told Reuters.

Central European countries and the Balkans have been used by Hollywood for years for their dramatic scenery, mix of architectural styles and cheaper filming costs. If a movie or series is a hit those locations can become hugely popular with visitors.

"The film and Game of Thrones have changed Dubrovnik for sure," said tourist guide Ivan Vukovic. About 1,000 tourists join a Game of Thrones tour every day, he said.

New souvenir shops were opened and jobs created for tourist guides and locals assisting in film productions out of season.

"All of this created a big economic boom," Vukovic said.

Trump did not provide details about the timing of tariffs, leaving executives wondering how they could be applied to the film industry.

Participants at the Cannes Film Festival, which opened on Tuesday, continued a cautious business-as-usual approach after the initial shock by the tariff announcement.

Mate Frankovic, the mayor of Dubrovnik, which receives about 1.4 million tourists a year, said he did not expect the crisis to last long or seriously affect film productions and tourism in Dubrovnik.

"I honestly cannot imagine a single serious US film and large production without including a major European city," he said.