Montreal coach Michel Therrien made the announcement after Thursday's morning skate, though he wouldn't give details on what is ailing Weise, saying only that he has a "body injury."
Moore received a two-game suspension for the hit, which occurred midway through the third period of Game 5 on Tuesday in Montreal.
The Canadiens won the game 7-4 to avoid elimination and force Thursday's Game 6 in New York (CBC, CBCSports.ca, 7:30 p.m. ET).
Moore was given a major penalty and ejected from the game after catching Weise with a blindside open-ice hit that knocked Weise's helmet off and left him wobbly.
Weise left the game briefly but returned to play three more shifts.
Emelin a game-time decision
Therrien also said Thursday that Alexei Emelin is a game-time decision. The defenceman sat out Game 5 with a suspected knee injury.
Goalie Carey Price, out since the third period of Game 1 with a suspected knee injury, once again took the ice in full equipment, but he is not expected to play in Game 6.
Back in the Montreal lineup for Game 6 is forward Brandon Prust, who returns from a two-game suspension for breaking Derek Stepan's jaw on a hit similar to the one that felled Weise.
Former Hab Raphael Diaz is expected to play for New York in place of the suspended Moore.
The Rangers' Daniel Carcillo, meanwhile, will meet commissioner Gary Bettman on Friday to appeal his 10-game suspension for jostling a linesman in the aftermath of the Prust hit.