The 16-year-old, who cannot be named for legal reasons, punched, kicked and stomped on his victim at Woodlands Community Sports in Cochrane Street on August 3, 2020.
He appeared at Falkirk Sheriff Court on Thursday, having pleaded guilty to assaulting the 18-year-old boy to his injury.
The court was told the incident unfolded while a group was playing football.
Procurator fiscal depute India MacLean said: “The accused was walking by, and punched him to the head. He has also kicked and stomped on him.
“The complainer curled up on the ground to try to protect himself and the accused continued to punch him on the head and body.”
The court was told the victim had a cut lip, swelling to the side of his head, scratches on his hands and reddening of his ribs, but didn’t require medical attention.
Defence solicitor Murray Aitken told the court his client’s 14-year-old friend had been bullied by the victim and received online threats.
He continued: “He’d been out that day with the 14-year-old who pointed him out, saying that was the chap who has been causing difficulties. Unfortunately he took it upon himself to go and speak with him initially, he says, with good intentions.
“He was of the view the complainer was smirking and not taking it seriously. The red mist descended and he behaved appallingly. He knows he’s done wrong and does genuinely regret what has happened.”
Noting the details of a background report, Sheriff Derek Livingston said: “My reading is he mixes with what might be called a bad crowd.”
Warning the teenager over his conduct, Sheriff Livingston: “Mainly, people who kick others on the head can expect a custodial sentence.
“Your client can be glad, because of his youth, there’s not been a custodial sentence imposed here. I hope this is the last time we’ll be seeing you in court.”
The teen was sentenced to a four-month, 6pm-6am restriction of liberty order as an alternative to custody, due to the time of his plea.