By Gina Cherelus

NEW YORK (Reuters) - With protests hitting many U.S. cities, the deadly ambush of Dallas police, and the ever-present threat of gun violence, four countries have urged citizens to be on alert if visiting the United States, and some black travelers are worried about making the trip.

Some African community groups in the United States and elsewhere told Reuters that family members of those already in America were scared by recent events, and some had been warned by relatives to reconsider any trip.

"When we talk to them in the community, some of the things that they say are, 'there are so many crazy things happening in your country that if I can avoid coming I won't come,'" said Ibrahima Sow, president of the Association of Senegalese in America.

The Bahamas, Bahrain, New Zealand and the United Arab Emirates have warned citizens to be on guard if visiting U.S. cities rocked by sometimes violent protests that erupted over the last week following the fatal shootings of two black American men by police.

In stark terms, the Bahamas told young men especially to exercise "extreme caution" when interacting with police. "Do not be confrontational and cooperate," it said.

Sow said concerns about travel to the United States have been high since the Sept. 11, 2001, attacks. His group gives specific guidance to Senegalese travelers about how to behave with the police.

"We say there are things that you need to know if you are stopped by the police," Sow said. "We tell people to be cautious and when you get stopped in the streets by police don't move your hands, don't move your body, don't do anything."

'JUST AWFUL'

Some similar organizations in Europe said they also had longstanding advice that they give to members who are thinking about visiting the United States.

"I would feel less safe there than four or five years ago," said Louis-Georges Tin, president of France's Council of Black Associations, which gathers about 100 organizations in France to fight against racism and promote French ties with Africa.

That sentiment was echoed by others including Paul Rose of britishafrocaribbean.com, a website and think tank for the British Afro Caribbean community. He said social media such as Facebook, YouTube and Twitter had raised awareness of what he called "atrocities" by U.S. police.

"You don't want to find yourself in situations where you are confronted with the police," Rose said. "Look at the incarceration rates of black men in America, look at the effects of the economic downturn, which affect the black community far more. The stats are just awful."

Some people already living in the United States said the turbulence is sometimes too much for their visiting relatives, even if the perception is worse than the reality.

"I have a cousin who is here right now and she's even scared to go outside to 34th street," said Zainab Bunduka, a 55-year-old employee at New York City's North Shore Hospital. She is originally from the West African country of Sierra Leone, which was ravaged by civil war during the 1990s.

"She's scared because we don't have all these gunshots back home," said Bunduka.

(Additional reporting by Karin Strohecker in London and Chine Labbe in Paris; Writing by Daniel Wallis; Editing by Frances Kerry)