The Green Bay defender put his hands on a Detroit official who was trying to tend to an injured player late in the game at Lambeau Field ... and the rookie linebacker's actions were so disturbing, referees actually ejected him from the game.

The 22-year-old first-round pick was panned for the move -- particularly after the Buffalo Bills had just credited one of their trainers with helping save Damar Hamlin's life earlier in the week -- and on Monday morning, Walker issued an apology for his actions on his Twitter page.

"I want to apologize publicly about what happened Sunday night," said Walker, who led the Packers in tackles this season. "I reacted off of my emotions again and take full responsibility of making another stupid decision."

"Since then I've questioned myself on why did I do what I did when the trainer was doing his job!! I was wrong!!"

Walker -- who was actually ejected earlier this season against the Bills for shoving a Buffalo assistant in a similar fashion -- also explained his actions that followed the ejection ... saying he was kicking himself in the stadium tunnel after he had "messed up again."

"[I] was wrong for what I did and couldn't believe I did it again," Walker said. "To the Detroit lions and to the entire training staff including the person I did that too. I'm sorry."

Walker says he will accept whatever punishment will come his way.

Packers head coach Matt LaFleur, meanwhile, called the incident "unacceptable" ... and said he holds his players to a "much higher standard."