Kings coach Darryl Sutter thought Keith got off easily with a double minor after opening a gash on Carter's face during the Blackhawks' 3-1 loss to the defending Stanley Cup champions in Game 3 on Tuesday night.
Keith clipped Carter during an exchange well behind the play in the second period. After Carter took a short hack at Keith's hand while the defenceman bent down to pick up his glove, Keith responded by skating behind Carter and hitting him in the face with a one-handed swing of his stick, dropping Carter to the ice.
"Yeah, it was accidental," Keith said. "Obviously, I wanted to give him a tap, but not where I got him. I felt bad. I'm glad to see that he came back. It was just a scuffle. It was an accident."
The injury forced Carter, who wears a visor, to miss the Kings' ensuing four-minute power play, which went nowhere. Carter, who scored two goals in the Kings' Stanley Cup-clinching victory over New Jersey last year, has six goals in this post-season, sharing the Kings lead with Justin Williams.
Keith apparently attempted to apologize to Carter on the ice after Carter returned to the game.
Sutter thought Keith deserved a harsher penalty for his actions, calling it "retaliation."
"I didn't think it was a four-minute penalty," Sutter said. "Thought it was a wrong call. ... That's three head injuries now in the playoffs for us. I don't know how to answer it. It's retaliation with a stick. It's not a high stick. Whatever they want to call it, they'll call it. Don't even need video."
The Kings lost centre Jarret Stoll for six games in the second round with an apparent concussion from an illegal hit by San Jose's Raffi Torres. Stoll returned for the conference finals, but the Kings then lost leading scorer Mike Richards for the past two games after a big hit late in Game 1 from Chicago's Dave Bolland.
Carter led the Western Conference with 26 goals during the regular season. His midseason arrival from Columbus last year was a factor in the Kings' improbable surge to their first Stanley Cup title.
Keith also is a Stanley Cup winner and the Blackhawks' top defenceman, recording a team-leading 26:47 of ice time in Game 3.