This kid was no killer — but some callous Bronx cops sure treated him like one.

Instead of earning himself a simple trip to the principal’s office, a terrified 7-year-old boy was hauled out of class, handcuffed like a hardened criminal and “interrogated” by police for a grueling 10 hours — all over a playground dispute involving $5, his family is charging.

“My son was crying, ‘Mommy, it wasn’t me! Mommy, it wasn’t me!’ I never imagined the cops could do that to a child. We’re traumatized,” Wilson Reyes’ distraught mom, Frances Mendez told The Post last night.

“Imagine how I felt seeing my son in handcuffs!’’ she said. “It was horrible. I couldn’t believe what I was seeing.”

The bizarre overreaction by cops came after the child had been accused of swiping $5 from another student after school.

The money, which was supposed to be used for a school trip that never happened, had fallen on the ground in front of Wilson and two other boys, and one of them scooped it up.

Wilson was falsely accused of taking it, and he scuffled with one of the kids.

Officers showed up at PS X114 on Dec. 4 at about 10:20 a.m., and handcuffed and held Wilson in a room there for four hours. They then hauled him off to the 44th Precinct station house for another six hours of interrogation and verbal abuse, according to a $250 million claim against the city and the NYPD.

The boy protested his innocence, to no avail.

“Reyes was handcuffed and verbally, physically and emotionally abused, intimidated, humiliated, embarrassed and defamed,” the documents say. He was then charged with robbery.

Mendez said that she and her sister first went to the station house, they were told they couldn’t see her son.

When cops finally allowed the pair to see the boy, they found the panicked kid seated in a shabby chair with his left wrist cuffed to the wall, Mendez said.

She quickly snapped a damning photo of the scene.

“My sister and I started crying when we saw him,” Mendez said.

Seth Acevedo, the boy Wilson was accused of punching and robbing, had been pushed around before by Wilson and other kids, his father Santiago Acevedo said.

“There were always teasing him because of his weight. Sometimes he didn’t even want to go to school because of it,” Santiago Acevedo, 63, told The Post today.

The city’s Law Department wound up dropping the robbery charge against Wilson on Dec. 26. Inspector Kim Royster said yesterday the story was “grossly untrue in many respects, including fabrication as to how long the child was held in the precinct which was less than half of the time mentioned.”

The legal papers say another classmate later admitted the theft.

Family lawyer Jack Yankowitz — who filed the claim with the city Comptroller’s Office Monday — blasted cops over the incident.

“It’s unfathomable, what the police did. The whole thing sounds so stupid. They were interrogating him like he was a hardened criminal,” Yankowitz said.

“If you have a child, a nephew, can you even imagine this happening to them?”

But law-enforcement sources insisted that Wilson was treated like any other young suspect.

“We responded to a 911 call of a robbery and assault . . . Eventually, [Wilson] was taken back to the precinct and placed in the juvenile room,” a source said.

“He was charged with robbery. The allegation was that he punched the kid and took his money. He took the money forcibly.

“The kid came into the precinct a little bit after 3 p.m., and he was out by 7:45 p.m. . . . That’s standard for a juvenile arrest.”

School officials said the incident took place off school grounds and referred questions to the NYPD.

Additional reporting by Bob Fredericks