He has been suspended until a hearing, which will be held once the police and the football federation have completed their investigations.
Tauranga City manager Kelvin MacDonald said he was about 50 metres away from the assault.
Before he realised what had happened, a group gathered around the referee and a couple of his players were holding back the Manukau City player.
"They wanted to get in between him and the referee to pull him off and march him away and plenty of people ran over to the referee," Mr MacDonald said.
Mr Gattsche had blood pouring from his mouth and looked in a bad way but was "professional to the end".
"He was tough - he didn't hit the ground, and stayed on his feet. He wasn't good, though ... but he was still conscious and was still in charge. He called the match off and passed his record on to the groundsman, then he was led off the field to the ambulance."
Everyone was standing around in silence and in disbelief at what had happened.
Manukau City did not return calls.
Last night, Mr Gattsche, a father of two in his late 40s, was waiting for a surgery slot at Middlemore Hospital in Otahuhu.
His wife said he was "doing good".
New Zealand has almost 2000 volunteer soccer referees, who donate their time and are reimbursed only for a few expenses.
"They have to buy their own gear, they have to get themselves to and from games, they have to pay for their own referee development courses - so very much they're volunteering for the game," said Auckland Football Federation chief executive David Parker.
The federation was taking Wednesday's incident seriously and was waiting for reports from the two match officials at the game and from both clubs.
The player would also have the opportunity to "bring forward any extenuating circumstances or to completely deny it, as sometimes happens", Mr Parker said.
Players had assaulted referees before. It was regrettable and incidents like Wednesday's were dealt with "in as firm a way as we can".
"We find it hard enough to get referees to want to come and do what they do. They are putting themselves in a position where they are arbiters of a game and shouldn't be treated this way. We've taken an extremely dim view of cases like this when proven."
Mr Parker said it was common practice to have a judicial hearing within seven days of the incident, after which it was decided what sanction would be imposed.
That could be anything from a "slap on the wrist" to the equivalent of a life suspension.
The federation can also ban a player indefinitely. After 12 months, the player is able to appeal to the board of New Zealand Football for reinstatement.
Occasionally, Mr Parker said, offences could be deemed common assault - as happened on Wednesday.
In these cases, the federation would call in the police.
The federation considered assault on a match official the most serious offence.
Counties Manukau police spokeswoman Ana-Mari Gates-Bowey said officers were speaking to witnesses, but no charges had been laid.
