Montreal responded with a good opportunity as the home side failed to clear a loose ball in their box, which was seized upon by Didier Drogba, but his close-range effort was well blocked by Bobby Shuttleworth.
Juan Agudelo caused problems for the visitors down the left and his good work almost carved out a goal for his team when he teed up Lee Nguyen on the edge of the box, but Jon Busch made a good save to deny the midfielder.
In the second half, the Impact took the lead when Ignacio Piatti was allowed to drive at goal and he then burst past two defenders before blasting an effort beyond the reach of Shuttleworth.
New England almost got back into the game as Nguyen collected the ball on the edge of the area, but Busch made a scrambling save to keep out his low drive.
Patrice Bernier should have secured the win for the Impact in the dying minutes when he received the ball inside the box, but the midfielder lost his composure at the vital moment, sending his effort over the bar.
However, the visitors held out for the win and booked their place in the post-season, meanwhile the Revolution are forced to wait until the final day of the regular season to attempt to seal a playoff berth.