No timetable was given for his return.
Pettersson, who leads NHL rookies in goals (five) and points (eight), was injured on a hit by Florida Panthers defenseman Mike Matheson on Saturday.
"He's doing better. Better yesterday and better today again," Green said. "I didn't know what happened. None of the players on the ice knew, none of the players on the bench knew what happened."
Matheson had a hearing with the NHL Department of Player Safety on Monday.
"It's tough to see an injury like that," Canucks forward Bo Horvat said. "It [stunk] at the time because none of us saw the hit. None of us knew the extent of the hit until after the game. ... It's tough that he got hurt. You lose a player like that, who's if not our best player, one of the best players in the League right now in my opinion. To lose a guy like that, it definitely, it [stinks]."
The Canucks also will be without forward Jay Beagle for six weeks because of a fractured forearm. Markus Granlund could replace him at fourth-line center.
Forward Adam Gaudette was recalled on Monday from Utica of the American Hockey League, where he had four points (two goals, two assists) in four games.
"I was down there in Utica and got things started off with the team there pretty well," Gaudette said. "It's exciting to be called back up, especially so soon. Those first four games, I think I learned more and more every game, and got better. I came back with a lot more confidence than I had during camp."
Gaudette, who could replace Pettersson on the second line, said he looks forward to playing with left wing Nikolay Goldobin and right wing Loui Eriksson.
"They are two great players and two skilled guys," Gaudette said. "I'm going to do my thing and get in there, mix it up a little in the dirty areas and just get them the puck. Find space to get open for them."
Vancouver plays the Pittsburgh Penguins at PPG Paints Arena on Tuesday (7 p.m. ET; SN1, ATTSN-PT, NHL.TV).
