The U.S. Embassy in Mexico issued a security message Friday warning U.S. citizens to avoid the Pacific resort of Acapulco because of violence and protests.

In yet another blow to a coastal city once favored by U.S. movie stars and jet-setters in the 1950s and '60s, the embassy said its personnel "have been instructed to defer non-essential travel to Acapulco, by air or land," and added that it "cautions U.S. citizens to follow the same guidelines."

The alert noted that "protests and violent incidents continue in Guerrero state in response to the disappearance of 43 students there."

Demonstrators have blocked highways to Acapulco, hijacked buses and blockaded the city's airport to demand the government find the students who disappeared Sept. 26 in the nearby city of Iguala. Prosecutors say local police working for a drug gang probably turned the students over to gang members, who may have killed them and burned their bodies.

In early November, demonstrators blocked Acapulco's airport for hours carrying clubs, machetes and gasoline bombs, causing hotel reservations on a subsequent three-day holiday weekend to fall about 35 percent, said Javier Saldivar, head of Acapulco's business chamber. Hotel occupancy that should have neared 95 percent was only about 60 percent.

"We suffered a serious loss," Saldivar said.

While U.S. tourists account for about 55 percent of foreign visitors to Mexico, relatively few of them go to Acapulco any more. For example, while Mexico's most popular cruise ship port, Cozumel, handled 894 cruise ship arrivals in 2013, Acapulco had only 9.

Drug gang violence has also played a role. In recent years there have even been some shootouts on Acapulco's famed coastal boulevard, but those incidents have calmed somewhat in the last two years.

Acapulco was once a well-regarded destination. It was during a vacation there in the 1960s that novelist Gabriel Garcia Marquez came up with the idea for "100 Years of Solitude." It was there that Bill Clinton took a young woman named Hillary for a honeymoon in 1975.

But in the 1970s and '80s, the resort's infrastructure crumbled, and poor, crowded settlements sprung up inland from the bay, sparking rising problems of unemployment, crime and pollution.