A Christchurch man celebrating New Year's Eve with his family needed stitches in his head after he was attacked by a child and two teenagers next door.

The man, who did not want to be named but posted a photo of his injury online, said the problems began while his family set off fireworks at their Wainoni home.

A child from next door started throwing small apples at his family and he told them to stop.

The 12-year-old sprayed the family with a garden hose while they played with sparklers.

He sent his children inside and went to the neighbour's property.

The child's older brothers, aged 15 and 18, allegedly then forced him to the ground and hit him repeatedly.

"When they knocked me down I was just covered in blood from head to toe," he said.

"It was all a bit of a shock."

His wife and 63-year-old father went to help.

The 12-year-old hit his father across the back with a metal bar and took a swing at the man's wife, he said.

The man suffered a cut to his forehead that went "down to the bone" and a dislocated shoulder.

The man received eight stitches at Christchurch Hospital - six on his forehead and two in his mouth - and his arm would be in a sling for two weeks.

"I'm definitely going to have a scar," he said. "The whole thing is just so ridiculous."

Police yesterday issued a trespass notice to an 18-year-old man and two boys aged 12 and 15 on behalf of the injured man.

The 18-year-old was charged with assault with intent to injure and would appear in the Christchurch District Court on Friday.

The injured man said he was "satisfied" with that outcome.

He hoped all involved could "move on".

"I don't want to see anyone's lives getting ruined, but sometimes there needs to be a consequence."

The man had installed security cameras on his property.

He worried about having to continue living next to his alleged attackers and said his children no longer wanted to play in the backyard.