The Dutch winger believes that the hosts were not given enough credit ahead of the Champions League quarter-final first leg, and claims that Bastian Schweinsteiger's goal was a big positive for last year's winners of the competition.
"In the end, we can be satisfied with the 1-1," Robben told NOS. "At least it's better then 0-0. We scored an away goal, so that's a positive thing.
"I didn't like it that people from outside underestimated United. The media were talking about them as though they would be easy to beat. I mean, after all you're playing against United at Old Trafford.
"We have to move the ball quickly and find the space. We didn't create many major chances, but we're satisfied with 1-1. Next week we have to give it our best again."
The second leg of the tie takes place in Munich next Wednesday.