The 23-year-old was seen screaming at Bednar on the bench in a game the team dropped 5-3 to the Calgary Flames.
"That's unacceptable on my part," MacKinnon said on Friday, according to Sportsnet's Eric Engels. "I can't be doing that stuff... I was just really frustrated, but I love playing for Bedsy."
"We spoke after the game and Bedsy’s the least sensitive guy ever, so it’s all good."
MacKinnon said he became frustrated when the Avalanche didn't pull their goalie with the team trailing by two goals late in the game.
Bednar, meanwhile, held no hard feelings toward MacKinnon, and was happy to see his star player show passion.
"All of us, at the time, were frustrated. I thought we played two really good games, could've come out with four points," Bednar said. "To me (the outburst) didn't bother me at all. That's what I love about Nathan and about certain guys on our team is the fire and passion and emotion they play with, they have. That's what you need in this game... that’s what makes him so good, so I never want to curb that."
The club has lost eight of its last nine games, which could also be causing some frustration. The Avalanche will look to get back into the win column Saturday when they take on the Canadiens.