Three young troublemakers who assaulted a retired NYPD lieutenant in the Upper East Side were turned in to authorities by their parents following the release of their pictures by the police.

The teenagers, comprising two 13-year-olds and one 14-year-old, were taken by their families to the 19th Precinct station house on Friday, most likely after their parents recognized them in the surveillance images, as per a police insider.

“I guess they were embarrassed,” the source said.

They were all charged with second degree gang assault and second degree assault.

The group attacked the 65-year-old former cop at around 8 p.m. on Tuesday, after he intervened to prevent them from harassing a taxi driver at Park Avenue and East 84th Street, according to sources in law enforcement.

The victim was bashed with a backpack and punched in the face, sending him falling to the ground, the sources said.

“They were looking for trouble harassing everyone they saw,” said the victim, who did not want to be identified. “When they started to bother the cab driver, I went over and told them to leave him alone. That’s when one coward hit me from behind with a backpack.”

He suffered minor injuries to his face and knee, and refused medical attention, cops said.