Peter Budaj stopped 16 shots for Montreal, which took over first place in the Northeast Division with 63 points.
Second-place Boston has 62 points and will conclude its season Sunday against Ottawa in a game rescheduled due to the Boston Marathon bombings. That contest will decide the No. 2 seed in the Eastern Conference.
The fifth-seeded Toronto got its lone goal from Phil Kessel.
James Reimer was pulled in the third period after yielding four goals on 23 shots.
Ben Scrivens relieved and made five stops the rest of the way for the Maple Leafs, who finished with a 26-17-5 record.