"We'll be working with the police and the school to identify the person," Mr Crawford said.
There were a lot of witnesses but none had come forward.
"We understand they closed ranks on the person, but we'll certainly be dealing very heavily with the school (De La Salle), with the headmaster and the chairman of the board of trustees."
Mr Crawford said the referee was okay after the attack. "It's just wasn't a very pleasant thing to happen after the game."
There was "zero tolerance" to physical or verbal abuse against referees, he said.
"If there are any incidents we'll take it as far as we can through judicial measures. Whether it be a player or a coach, we'll take it to the police."
An official complaint had been made to police, he said.
The Auckland Secondary Schools Rugby Association and Auckland Rugby will also be involved in investigations into the incident.
De La Salle College principal Myles Hogarty was unable to be contacted today.
In a school newsletter on Friday he said the school had three teams in finals games over the weekend.
"They will play with great heart, passion, skill and sportsmanship while proudly wearing the De La Salle crest on their chests," he said in the newsletter.
Auckland Grammar School principal John Morris said today he couldn't comment until he had spoken with the team's coach, Mark Bella, today..
A timeline of violence at sports games
* June 30: Two Porirua men attacked supporters and the coach of the opposing team at an under-11 rugby match at Porirua Park. Both victims were punched in the head and the game was called off.
* May 19: A parent watching a children's rugby game stormed onto the field and grabbed the referee's throat at an under-10s match at Papatoetoe Club.
* April 25: A soccer player punched volunteer referee Len Gattsche, breaking his jaw in three places, during a soccer match between Manukau City and Tauranga City United.
* August 13, 2011: Five Otahuhu Rugby Club players were banned for life after assaulting a referee and breaking his hand at the conclusion of an under-19s match.
* August 15, 2009: Students from Auckland's Kelston Boys High School and Auckland Grammar School were suspended from playing rugby for up to 14 weeks after a brawl during a rugby semi-final. The fight broke out when the game finished, with Auckland Grammar winning and the final score 20-9.
