Harbaugh says Matthews threw one punch and slapped 49ers left tackle Joe Staley when they tussled after Matthews' late hit on quarterback Colin Kaepernick in the second quarter of San Francisco's 34-28 season-opening win Sunday.
"I think that young man works very hard on being a tough guy," Harbaugh said Monday of Matthews. "He'll have some repairing to do to his image after the slap."
Matthews had promised leading up to the game that Green Bay would target Kaepernick, who ran for a quarterback-record 181 yards against the Packers in the playoffs eight months ago, and Matthews did just that. On the play, he threw his right arm around the lower part of Kaepernick's neck.
"If you're going to go to the face, come with some knuckles, not an open slap," Harbaugh said Monday.
Staley, who was a guest on ESPN Radio's "Sedano & Stink" on Monday night, was asked what he thought about his coach's comments.
"Those are his words. Coach Harbaugh is being Coach Harbaugh," he said. "I think myself in that situation, I saw my quarterback being hit late out of bounds and instinctually it kind of took over that I felt I saw something that shouldn't happen on the football field and I tried to defuse the situation. ...
"I didn't go over with any malice or bad intent. I kind of just wanted to go over and let him know that that's not going to happen, especially on our home field."
In Green Bay, Packers coach Mike McCarthy defended his star linebacker.
"Clay Matthews is not a dirty player, by no means," he said. "I addressed Harbaugh's comments in the team meeting and as always we'll stay above it."
Matthews conceded Sunday that the late hit "wasn't very smart."
"I had already committed to hitting the quarterback. I guess I should have figured he was going to step out of bounds," Matthews said. "But it's nothing personal. I went up to him later and was joking around with him. But not a very smart play. And that's kind of the end of that."
Said Kaepernick on Sunday: "If intimidation is your game plan, I hope you have a better one."
ESPN.com 49ers reporter Bill Williamson, ESPN.com Packers reporter Rob Demovsky and information from The Associated Press contributed to this report.