Schallibaum was already going to miss Saturday night's game against Houston after he received an automatic one-game ban for being sent off in Montreal's win 2-1 over D.C. United last Saturday.
But MLS commissioner Don Garber suspended the Impact head coach for an additional game and fined him US$5,000 Friday "for his repeated misbehaviour."
Schallibaum, who has been ejected from games three times this season, will also miss Montreal's road game in Philadelphia on Aug. 31. He also served a one-game suspension for stepping on the field in a game against the Colorado Rapids.
"I'm very disappointed because I did something but it was not so very, very bad," Schallibaum said after practice Friday. "So that's a decision from MLS and the problem is I cannot defend the decision. I must accept it because I have no choice."
Schallibaum and United head coach Ben Olsen engaged in their heated confrontation following a hard aerial challenge between D.C.'s James Riley and Montreal's Justin Mapp, which sent the Impact player clattering into the midfield camera.
Olsen and Schallibaum were sent off while Riley was issued a yellow card. Olsen had his automatic one-game suspension and fine rescinded on Friday.
"I'm happy for him but that's a decision also for MLS," Schallibaum said. "He did the same thing as me, I think, and that's a part of the decision from MLS that I can't explain. You must ask the guys from the MLS why I have two, and the other has not."
Assistant coach Mauro Biello will assume Schallibaum's duties once again against Houston, which is fifth in the Eastern Conference with 36 points, two behind the third-place Impact.
Midfielder Patrice Bernier was a bit surprised about the severity of Schallibaum's discipline.
"He got sent off and you expect a game because you know that's the protocol," said Bernier, one of five players who did not travel with the team to Guatemala for Wednesday night's CONCACAF Champions League game. "Two games? I guess it's maybe because the club has been on top of the MLS radar so they felt that maybe they needed to extend it.
"It's tough but the coach is still there every day of the week for training and we have to perform. We're the ones who play on Saturday."
The Impact were delayed in returning from Guatemala and had to cancel Thursday's training session. Montreal lost 1-0 to CD Heredia in Guatemala City in their second group stage game.
In addition to Bernier, other veterans who remained in Montreal this week were Mapp, Alessandro Nesta, Matteo Ferrari and leading scorer Marco Di Vaio, who scored his 12th and 13th goals of the season in Saturday's win.
"Obviously it was a difficult trip in Guatemala," Biello said. "We were hoping for a better result and we have a very difficult game now against Houston. We'll face a team that's on the rise and a team that's been there almost every year at the end of the year. They've been playing good soccer of late and we need to be ready mentally to play against a team that will put their best team and try to get ahead of us in the standings."
The Dynamo have lost just once in their last six MLS games (4-1-1). Houston also had a mid-week trip for a CONCACAF Champions League game, a scoreless draw in Trinidad and Tobago against W Connection.
"They were a little bit luckier than us and they got the away point in Trinidad," Biello said.
One bright spot in the Impact's trip to Latin America was the unique local cheering section supporting the team, and more specifically, one of its players, defender Jeb Brovsky.
Brovsky travelled to Guatemala with his new bride in December to do charitable work with orphans. Returning there to play with the Impact, he spearheaded an outing that saw 450 Guatemalan children and 100 local volunteers take in the game.
"For all those kids, about 99 percent of them haven't been out of their own communities before, let alone a professional soccer match," Brovsky said. "So to have them there together making a bunch of noise for 90 minutes and to take a bus, to get a new bag, a new t-shirt, I definitely teared up after the game, that's for sure."