Robidas was knocked unconscious on the play late in the third period of Saturday night's 3-2 win by the Predators at Nashville.
Robidas, who was coming to the defence of star centre Mike Modano, was assessed a minor for charging on the play, and Tootoo received a double-minor for roughing.
Robidas was carried off the ice on a stretcher and was taken to hospital. He's out at least a week after sustaining a concussion.
"In reviewing this incident, Stephane Robidas appeared to be initiating a confrontation by approaching Jordin Tootoo," NHL senior executive vice-president and director of hockey operations Colin Campbell said in a statement. "While a player is entitled to defend himself, Mr. Tootoo's forceful blow to Robidas' head was an overly aggressive and inappropriate response.
"The fact that Mr. Tootoo's actions resulted in an injury to his opponent also was a factor in this decision."
Tootoo, 24, has three goals, four assists and 104 penalty minutes in 61 games this season. Robidas, 30, has 17 assists and 82 penalty minutes in 71 games this season.
Predators general manager David Poile said the team disagreed with the suspension, but did not plan to appeal.
"Jordin was put in a very difficult situation with Robidas confronting him," Poile said in a telephone conference. "I don't know what he was supposed to do. All he could see was a player coming at him with his arms up and certainly looking like he's ready to enter into some form of confrontation. I think Jordin did what I think everybody would do, and he reacted and threw a punch."