Brentford twice came from behind to take the points in the dying minutes as Clayton Donaldson's brace either side of Forrester's strike clinched the points in an emotion-charged end-to-end clash.
Ryan Lowe and Stephen Gleeson had twice put the visitors ahead with goals in either half, but Donaldson had the final say.
Robinson said: "I thought a draw would have been a fairer result, but this is a very tough place to come and play. They have players who can hurt you.
"In the end we scored two quality goals and I could not fault the effort of my players. We lost the game fair and square and we move on to the next one."
It was the third time in as many seasons Brentford had struck late in the game to deny the Dons and Robinson added: "We knew what to expect, but to lose it so late was disappointing.
"Having said that my players deserve a pat on the back for their effort. We won't dwell on it and will regroup and go again."