A Brooklyn man told a driver who had parked too close to a hydrant that he would protect his car from ticket agents — and then beat him when he wouldn’t cough up $5 as payment, law-enforcement sources said.

The incident began at 9:25 a.m. Saturday after the victim parked on Jefferson Avenue near Nostrand Avenue in Bedford-Stuyvesant, cops said. Shawn Walker, 32, who was standing nearby, allegedly offered to keep an eye on the car.

Walker asked for the five bucks when the driver returned and allegedly pummeled him when he refused, sources said. He was arrested on charges of attempted grand larceny and assault.