Celtic now sit bottom of Group C as goals from Lars Stindl and André Hahn ensured the German visitors left with all three points.
Toure, who earned praise for his performance in the previous match against Manchester City, was culpable at both Gladbach goals. In the first instance, he attempted to shepherd the ball out of play, only to have Hahn nick it off his toes, allowing Stindl to fire home. At the second goal his sloppy pass allowed Stindl to release Hahn, and the striker found the back of the net from 10 yards.
The 35-year-old refused to hide from his mistakes after the match, agreeing to speak to the BT Sport cameras alongside captain Scott Brown.
He said: “In that kind of competition you can’t afford to make that kind of mistake. I have to blame myself because it was a simple action just to put the ball to the side. I like to let the team keep the ball and I was overconfident. Second goal, the same thing.
“I don’t want to make a mistake but mistakes happen. Even though I’m 35 now I’m still making a 16-year-old’s mistake in the game. It showed that at that kind of level, the game is very fast and you really have to concentrate for 95 minutes.”
His captain insisted the loss, which leaves Celtic needing to take something from their away trip in Mönchengladbach in two weeks time, was the fault of the team and not Toure himself.
Brown said: “People make mistakes, everyone made mistakes today. That’s football, we have to bounce back. We try to play football from the back. That’s how the gaffer wants us to play.”
Manager Brendan Rodgers added: “He’s a top professional. He’s been outstanding since he’s come in here. But we ask them to play and mistakes are going to happen.”