What a slap in the face.

A Bronx lout smacked a Parks Department horse in the face on Sunday — and the agency refused to do anything about it.

The cruel horseplay occurred at around 6 p.m. in Van Cortlandt Park, as Parks Enforcement Patrol officers were trying to break up an unruly gathering of revelers, sources said.

As mounted units moved in, Franluis Ruiz, 25, was seen striking one of the horses, 10-year-old Teddy, in the face.

The blow caused the poor animal to recoil, video shared with The Post shows.

The Parks officers could have charged Ruiz with “killing or injuring a police animal” — a misdemeanor punishable by up to a year in jail and up to $1,000 in fines, according to New York penal law.

Instead, the officers slapped Ruiz with a $100 ticket for allegedly smoking a hookah in the park and a disorderly-conduct violation punishable by up to 15 days in jail or a fine of up to $250, according to copies of the citations.

The Parks Department claimed it didn’t put its hoof down because Teddy wasn’t seriously injured.

“Teddy is a valued member of our Parks Enforcement Patrol team. As such, his safety is of concern and we are happy that he was not seriously injured during this unacceptable incident,” said spokeswoman Crystal Howard.

But the head of the DC 37 Local 983 union representing PEP officers said they didn’t make the collar because the cops have told them the charges wouldn’t stick and the city is afraid of lawsuits claiming false arrest.

“Our members are no longer making the arrests because now they have to worry about a liability issue of making a false arrest,” said the union’s president Joe Puleo. “It’s about time that the Parks Department stop putting these horses in harm’s way.”

Animal-rights lawyer Karen Copeland of Manhattan was outraged that Ruiz didn’t face stiffer penalties, arguing that the uniformed parks officers were “acting under the color of authority” when their animal was attacked.

“That’s striking out at that authority,” she said, comparing it to bashing a police cruiser with a hammer. “I think it was also animal cruelty. It was unprovoked and there’s absolutely no defense to an act against an animal like that.”

Copeland noted that, if not for Teddy’s training and the control exercised by his rider, the horse could have reared back and bolted — potentially injuring both of them and bystanders.

Ruiz could not be reached for comment.