Mayor Bill de Blasio has again spit in the face of city cops — using the word “allegedly’’ to describe the vicious mob attack on two NYPD lieutenants, outraged police reps said Sunday.

Bending over backward to praise the city’s anti-cop protesters for their “peaceful’’ behavior — even as some chanted on Saturday night, “What do we want? Dead cops! When do we want it? Now!” — the mayor said the attack was “an incident . . . in which a small group of protesters allegedly assaulted some members of the NYPD.”

“When cops are the accused, the word ‘alleged’ never enters into the discussion,” fumed Michael Palladino, president of the NYPD Detectives’ Endowment Association.

Ed Mullins of the Sergeants Benevolent Association called de Blasio a “total nincompoop” for his handling of the situation.

“His actions are contributing to the injuries that are being received by the NYPD,” Mullins said.

“Maybe he should be out there to take the broken nose for the lieutenant. Ask him if he’d be willing to stand out there and take the punches for the cops,” he added.

Some cops were even comparing de Blasio to his political mentor, ex-Mayor David Dinkins, who was reviled for apologizing to the family of a drug dealer killed while resisting arrest, and then paying for the thug’s funeral, in the early 1990s.

“[De Blasio] is at a crossroads right now where he’s going to have to figure out what side he’s standing on,” a source said. “With cops ending up in hospitals, he can’t play both sides forever.”

The two lieutenants who were beaten on the bridge work in the department’s Legal Bureau — and were on the scene to ensure that protesters’ civil rights were respected by cops.

They were punched and kicked in their faces and heads when they went to arrest a CUNY professor, Eric Linsker, 29, of Brooklyn, as he tried to heave a garbage can onto other cops from an elevated walkway.

“You throw that from the upper level to the lower-level roadway, and you could kill someone,” said a police source who estimated that the can weighed “at least 40 pounds.”

The incident was among several outbreaks of violence and hostility toward the NYPD during Saturday’s massive protest over recent police killings, including the July 17 chokehold death of Eric Garner on Staten Island.

When cops are the accused, the word ‘alleged’ never enters into the discussion. - Michael Palladino, NYPD Detectives’ Endowment Association president

Last week, a grand jury cleared NYPD Officer Daniel Pantaleo of criminal wrongdoing in Garner’s caught-on-camera takedown for allegedly selling loose cigarettes.

In addition to the bridge beating, a group of protesters shattered the rear window of a marked NYPD car with two traffic agents inside on Madison Avenue near East 28th Street.

A group of men wearing masks and black clothing surrounded the vehicle around 4:45 p.m. and began kicking it before someone hurled a garbage can at the rear window, which was then destroyed by someone wielding a metal pipe, cops said.

A video posted on YouTube also showed activists marching through Murray Hill while chanting the anti-cop vitriol, “What do we want? Dead cops! When do we want it? Now!”

A de Blasio spokesman wouldn’t say why said the mayor chose to include the word “allegedly” while describing the Brooklyn Bridge attack.

“Last night, the mayor could not have been more clear that violence in protests will not be tolerated and that our police should be commended for the professionalism and service they have displayed throughout these marches,” spokesman Phil Walzak said.

Additional reporting by Aaron Feis

Video credit: Chris Nooney