For the first time in seven years, New York City officials expect the number of foreign visitors to decrease, a drop they attribute to the protectionist policies and rhetoric of President Trump — saying that those moves are scaring off many of the visitors who have helped fuel the city’s robust growth since the last recession.

On Tuesday, the city’s tourism marketing agency, NYC & Company, plans to announce that its forecast for international visitors has turned from positive to negative since Mr. Trump was elected in November. The city now expects to draw 300,000 fewer foreigners this year than in 2016, when 12.7 million international visitors came, a decline that will cost businesses in the city that cater to tourists at least $600 million in sales, the agency estimates.

Fred Dixon, the chief executive of NYC & Company, said Mr. Trump’s statements and actions had changed perceptions about the hospitality of the United States just as prospective tourists are making vacation plans for 2017. “The Europeans start coming to New York around Easter and continue through summer,” Mr. Dixon said in an interview. “That’s when you’ll see the rhetoric out of Washington really having an impact on travel.”

He said American tourism promoters were “just sort of holding our breath” in anticipation of a revision of Mr. Trump’s aborted plan to ban arrivals from seven mostly Muslim countries. “Regardless of the specifics, it’s pretty clear the message is going to be unwelcoming,” Mr. Dixon said.