The disciplinary committee gave suspensions to the Seattle Sounders midfielder, Chicago right back Lovel Palmer and New York center back Armando.
The MLS disciplinary committee handed down the suspension and an undisclosed fine after replays showed Dempsey striking Toronto defender Mark Bloom in an off-the-ball incident. Dempsey's appeal of the suspension was denied.
The U.S. national team captain will miss Seattle's match at the Montreal Impact on Saturday and at home versus the Columbus Crew on March 29. He will be eligible to return when the Sounders travel to face the rival Portland Timbers on April 5.
The disciplinary committee also gave Chicago Fire right back Lovel Palmer a two-game suspension and New York Red Bulls center back Armando a one-match ban for incidents this past weekend. Montreal midfielder Justin Mapp was fined an undisclosed amount for simulation.