COLUMBUS -- Boston Bruins winger Brad Marchand doesn't regret punching Blue Jackets defenseman Scott Harrington in the back of the head at the end of Game 3, though he did say Wednesday that his actions were "unnecessary."

Bruins coach Bruce Cassidy plans on having a chat with Marchand about the winger's discipline. Marchand has taken two penalties in the second-round series that have directly led to Columbus power-play goals.

But an even bigger hot-button issue emerged Tuesday as Marchand -- long known as one of the league's biggest agitators -- came up on Harrington from behind and punched him in the head during a stoppage late in the third period of Columbus' 2-1 win in Game 3 on Tuesday night.

Marchand was not called for a penalty, and the NHL Department of Player Safety decided not to implement any supplemental discipline other than a warning.

NHL commissioner Gary Bettman, asked about the punch while attending a Canadian Parliamentary hearing on concussions, said Marchand should have been penalized and, if it happens again, "he should look forward to a suspension."

Marchand called the punch "a reaction" after, he said, his teammate Jake DeBrusk was bullied in front of the Blue Jackets' net. Marchand said DeBrusk took "about six punches there from two guys" and therefore he felt he needed to defend his teammate.

"Having to talk about it today, is probably not something I'd go back and do it again," Marchand said Wednesday.

"I'm not overly concerned about what's said in the media and what fans say, and stuff like that. It was an unnecessary play, but it is what it is. Games go on, and I'll worry about the next one."

The Blue Jackets lead the series 2-1. Game 4 is Thursday in Columbus.

Entering these playoffs and through the first round, a new narrative was emerging regarding Marchand: The NHL's ultimate troll had turned a new leaf after being suspended six times over seven years for penalties such as slew footing, elbowing, clipping and spearing.

After last year's playoffs were marred by Marchand's unusual behavior of licking two different opponents, the NHL's Department of Player Safety privately and publicly asked Marchand to tone things down.

The 30-year-old Marchand made a commitment to stay out of trouble.

"I've got to cut that s--- out," Marchand said after the Bruins were eliminated by the Tampa Bay Lightning last spring. "After having a couple days, kind of looking back on the year and seeing what's happened the last few days with all the media and everything, I think the biggest thing for me now is to really take a pretty hard look in the mirror and realize the actions, some of the things that I'm doing have much bigger consequences.

"... I think it's kind of gotten to the point where the last thing I ever want to do is bring the embarrassment to my teammates and the organization that it did."

Marchand, the winger on Boston's top line, went the entire 2018-19 regular season without any discipline from the Department of Player Safety.

He went on to have a breakout offensive campaign, becoming the Bruins' first player to reach 100 points since Joe Thornton in 2003. Over the past three seasons, no other left wing -- not even Alex Ovechkin -- has more points than Marchand's 270.

"We need him on the ice," Cassidy said Wednesday.

Marchand leads the Bruins with nine points this postseason, but he's been scoreless in the three games against the Blue Jackets.

Earlier in the playoffs, the Bruins' Torey Krug told ESPN that he noticed Marchand was making a concerted effort to change his ways.

"The other part is his natural maturation into a leader in this room," Krug said. "We know the weapon that he is on the ice to win hockey games. He's not doing anything to hurt the team, and that's become something we rely on. We need him to win hockey games, so he can't be doing some crazy things on the ice to hurt the team. He's realized that, and he's done a good job growing up."