NEW YORK — The underground acrobats who flip, somersault and pole-dance among New York City subway riders as trains roll are drawing a new audience – police officers.

The New York Police Department is cracking down on the subway showmen who use the tight quarters of the nation’s busiest transit system as moving stages for impromptu – and illegal – pass-the-hat performances. More than 240 people have been arrested on misdemeanors related to acrobatics so far this year, compared with fewer than 40 at this time in 2013.

Police Commissioner William Bratton acknowledges he is targeting subway acrobats as part of his embrace of the “broken windows” theory of policing – that low-grade lawlessness can cultivate a greater sense of disorder.

“Is it a significant crime? Certainly not,” Bratton said recently. But the question is, he added, “Does it have the potential both for creating a level of fear as well as a level of risk that you want to deal with?”

The subway acrobats say they’re just out to entertain, make a living and put a little communal levity in New York’s no-eye-contact commuting.

“We all, as New Yorkers, get these force fields around us. We just try to go inside the train and change the vibe,” said a performer named Besnkheru, who spoke on the condition that his full name not be used.

Hopping on and off trains one recent afternoon, Besnkheru sang to amplified recordings ranging from Michael Jackson to Latin jazz while his performance partner, Domingo, danced, clowned and used the car’s bars and poles like playground equipment.

The pair got some glares but many smiles and a few dollars.

“It’s such a part of New York culture,” said rider Joli Tribuzio.

But other passengers resent becoming a captive audience in a cramped subway car.

“If the dancers make a mistake, someone could get hurt,” said Chief Joseph Fox, head of the NYPD’s Transit Bureau.