Barch was given a game misconduct after a dustup at the end of the first period in Florida's 3-2 win. The Miami Herald, citing an unidentified league official, said linesman Darren Gibbs overheard Barch use the slur against P.K. Subban, whose parents are Jamaican.
Barch left the dressing room before media members were allowed in for post-game interviews, The on-ice officials were not made available for comment.
"Personally, I didn't hear anything. I don't even know what happened, really," Subban said. "A couple of guys on the ice told me that something was said. I don't know what was said. I didn't hear it. As far as I'm concerned it's really out of my hands, so I don't really know too much about it."
Dineen was careful with his comments.
"Well, my take is we have an incredibly broken-up player in there who feels extremely bad that there was an insinuation that something inappropriate was said and now it's moved on to a league matter," Dineen said. "And obviously the Florida Panthers, Krys Barch and all of us are really shaken up by this, that there was an insinuation that something was said that was inappropriate."
"Again I'll leave it with the league right now, but I think this is always a very sensitive area for anybody and we'll let the facts play out and make sure that things are handled accordingly and move forward from there," he said.
Canadiens head coach Randy Cunneyworth had few details to offer.
"I know it was some sort of a game misconduct," he said. "I'm not sure what was said or how it was relayed or who exactly heard it. We're not aware of the exact words in any way and we don't think we'll ever find out."
"The bottom line is there is no room for that. Those things have to be (addressed immediately) and the referees are on the ball about those kinds of incidents," he said.
Shawn Matthias of the Panthers defended his teammate.
"You never want to see that and I know Barchy and I don't think that he's the type of guy that would do something of that nature," said Matthias, whose seventh goal of the season 3:08 into the third period broke a one-all tie.
Added teammate Kris Versteeg: "I don't think we can comment on it because it's obviously a touchy subject, but Krys is a good guy and he means no harm."
Tomas Fleischmann scored two goals, including an empty-netter with 40.2 seconds remaining that ended up being the game-winner.
Panthers goaltender Scott Clemmensen bounced back from his worst outing of the season the night before against the New York Rangers by stopping 17 of Montreal's last 18 shots. He replaced Jose Theodore 4:16 into the second period after Theodore left with a lower body injury.
The Canadiens struck first at the 5:37 mark of the first period when Travis Moen blasted a slapshot from the left circle 47 feet out past Theodore.
Fleischmann tied the game with a power-play goal 3:46 into the second period off assists from Stephen Weiss and Brian Campbell, and Matthias broke the tie 3:08 into the third with his seventh goal of the season.
After Fleischmann's empty-netter appeared to seal the victory, Montreal's Erik Cole made it a one-goal game at the 19:30.
Clemmensen turned away another Moen shot with 14 seconds left and then got help when Mike Weaver and Weiss blocked shots in the closing seconds.
Montreal lost its second straight game, both in the Sunshine State, and goaltender Carey Price dropped to 13-14-7 on the season with the loss as he surrendered three goals on 35 shots.
Florida maintained its four-point lead over the Winnipeg Jets, 3-2 winners over Toronto, in the Southeast Division and stayed five points ahead of the Washington Capitals.
Notes: With his assist on Fleischmann's tying goal in the second period, Weiss matched Olli Jokinen for the most assists in Panthers' history with 231. ... Fleischmann has scored three goals in two meetings with the Canadiens this season. ... Florida finished the month of December 5-2-1 on home ice. ... The Canadiens continue to struggle on the road as they fell to 9-11-1 away from home and are 0-2 against the Panthers this season.