A Staten Island man hit a 4-year-old boy in the head with a brick when an argument among neighbors over a roaming pit bull spiraled out of control, police said.

Marcillio Perez, 30, hurled the brick and hit young Josiah Green as Perez argued with a group near Stanley Avenue and Jersey Street at about 6 p.m. Monday, cops said.

“I just want to know why you would do that to kids,” said Josiah’s mom, Tanisha Green. “What do you have against my kids?”

The melee started when Green and several of her grown children approached Perez about leashing his pit bull, which neighbors claim regularly runs loose, terrorizing kids. One of Josiah’s siblings led the group complaining to Perez.

“[Josiah’s] older brother . . . confronted him, like, why would you let the dog loose?” Green explained.

“[Perez] ran to the side of my house near the ramp and grabbed two bricks and threw one of them and it hit [Josiah].”

Moments later, Perez allegedly tried to throw another brick — but he wasn’t able to lob it, as the boy’s irate siblings began assaulting him until cops arrived, police sources said.

Josiah was taken to Staten Island University Hospital, where doctors administered nine stitches, his family said.

“Yeah, I’m OK, I’m feeling good,” Josiah said Tuesday.

“The guy threw [the brick] at me.”

Perez was treated for unspecified injuries. He was charged with felony assault.

“I just want to know why he would do this to my boy. To a child,” Green said.

Neighbors said Perez is known for letting his pit bull run wild.

“The dog is always running around loose,” said one, who declined to identify herself.

“I have five kids, and the oldest ones walk home and I’m always looking out the window to make sure the dog’s not out on the street.

“He thinks he’s a badass,” the neighbor added.

“It doesn’t surprise me that this happened, and I’m sure he’s capable of throwing bricks — even at kids.”