The Auckland Rugby Union will also conducting an investigation into the incident once the police inquiry had finished.
A judicial convenor who will organise a panel for the investigation had been appointed, a spokesman said.
Supporters from both teams said that after the final whistle was blown, De La Salle supporters ran onto the field and a brawl erupted.
But two mothers of De La Salle players said the situation had been inflamed by the referee, who had imposed too many penalties against their team.
Tua Teara, whose son played in the match for De La Salle, said the team and their supporters were getting increasingly frustrated by the slow game.
She said the referee was too young to be in control of a finals match.
"There was a lot of whistle-blowing, a lot of stopping the game, I've never seen in my life so many whistles. If I had to count, there would be well over 50 whistles."
The referee was being assessed by the Referees Association during the game and Ms Teara felt that had put pressure on him to be harder on the players.
"At the end they all had enough of the whistle."
Another mother, Ula Mafoe, said the referee dominated the game, which escalated aggression.
"He didn't let the spectators watch a good game of rugby, a good final."
The referee said yesterday he had thought back on the game and he felt he had been correct in all his calls.
"I wouldn't do anything differently."
He said tension was high during the game, probably because it was a final, but the violence that followed the match was unexpected.
Both schools are also investigating the incident.
