Serie A's only representatives in the Champions League knockout stage hit the woodwork twice in the round of 16 first-leg encounter before conceding a late goal to Diego Costa, leaving them on the brink of elimination.
"We played a really good first half, we hit the post twice, created a lot of chances and then, right at the end, they scored their goal," team captain Kaka said.
"We had the chances to score but I don't like talking about bad luck. I'm optimistic about what I've seen this season," the former World Player of the Year added.
"The boss told us that we played well and we have to remember the good parts of our performance. We are beginning to harvest the first fruits of the new coach's work."
Seven-times European champions Milan are still rebuilding after the club decided to sell a number of top players, including Thiago Silva and Zlatan Ibrahimovic to help balance the books before the 2012-13 season.
"It's a shame about the result, but there have been a lot of positives this evening," Seedorf said.
"I saw dribbling, shots on goal, I saw the right spirit," he added. "We played a really good first half, though in the second we suffered a little physically.
"We were less lucid in the last 20 minutes because we paid the price for our efforts earlier in the game. These things happen in football."
- Sports & Recreation
- Diego Costa