Royal Caribbean Cruises has cancelled a planned call to San Juan, Puerto Rico, amid political strife in the US territory's capital city.

Thousands of protesters on Monday marched the city's streets, calling for governor Ricardo Rossello to step down two days after the reported discovery of inappropriate emails with closest aides.

"In light of current unrest in San Juan, Puerto Rico, we have canceled today’s call to San Juan," Royal Caribbean spokesman Owen Torres said in a statement to USA Today.