The Canadiens said Pacioretty will not return. The team said the left wing sustained a lower-body injury.
Pacioretty was pulled down by Jets forward James Wright while heading to the net. He was clutching his left leg as the Canadiens' medical staff came on to tend to him 13:02 into the game.
Pacioretty was not putting any weight on his left leg as he was helped from the ice.
Pacioretty, who missed a game earlier this season with an upper-body injury, has two goals and an assist in five games this season.