The Canadiens lost their fifth straight.
Pavelec turned aside five Montreal power-play opportunities in the second period and went on to boost his shutout total to nine over five NHL seasons.
Blake Wheeler scored his fourth and fifth goals of the season, putting Winnipeg in front on the power play just 3:18 into the game.
Tanner Glass scored in the first period and Wheeler tallied again 39 seconds into the middle stanza. Tim Stapleton wrapped up the scoring with 2:24 left in the third.
Winnipeg won for the seventh time in 10 games and moved two points in front of Washington for second place in the Southeast Division.
Carey Price gave up the four goals on 34 shots.