The Flying Donkeys had arguably had the better chances and even had a goal controversially ruled offside in the first half, but capitulated to Seedorf's stoppage-time stunner.
"I am pleased that the team reacted after last week's defeat to Bari. I was interested in the performance and on that front we delivered with tempo and aggression," said the coach.
"The result does not provide the just reward for the efforts of my squad. In the first half especially we had more chances than they did, so Milan had a bit of luck and also quality.
"Seedorf's goal was extraordinary, it's one of those strikes that makes this sport so wonderful to watch."