MK Dons boss Karl Robinson has branded Gary MacKenzie's actions in the draw with Huddersfield a "disgrace".
The defender was sent off late on in the match for what appeared to be a headbutt on Terriers striker Alan Lee, and will now serve a three-match ban.
"It was a disgrace what he did, he knows that, I won't condone it," Robinson told BBC Look East.
"He has been punished internally and he's accepted it like a man, which I knew he would."
Robinson added: "It's not acceptable in the game and it's not acceptable in society. I'm sure I can back Gary not to do that again."
MacKenzie, 25, conceded a penalty with his actions, but Lee Novak failed to convert from the spot.
Meanwhile, Robinson, reacting to rumours in the national press, has admitted he would be interested in taking Sheffield Wednesday striker Clinton Morrison on loan, but expects to be priced out of any potential deal.
"I hear [Wednesday boss] Gary Megson has said we've got to come up with some more money if we want to get him," he said.
"If Gary Megson doesn't want him, we'll take him off his hands, but it's got to be at a price we deem fit for this football club.
"We've not got the money that people think we have.
"But if a player like Clinton Morrison became available, he knows how much I rate him, he knows I'd like him to come here for a month, we'll just have to wait and see."