Sir Alex Ferguson's side have already qualified for the knock-out phase ahead of tomorrow's home clash with Besiktas and Fletcher said: "It was disappointing because we all knew that we can do better as a team. We'll use that defeat to make us stronger this year.
"We want to go back to the European Cup final and show that we are a better team than the one which lost to Barcelona. We're determined to win it this year.
"The lads knew that we were beaten by the better team on the night and we are respectful of Barcelona, but it's a horrible feeling to lose a final. We need to use that. We need to remember those images of us sat on the field having lost and use them to make us more determined this season."
Fletcher could only look on helplessly in the Olympic Stadium because he was suspended and says it was a horrible experience.
"It was very frustrating," he said. "To miss out on the final after working so hard to get us there was disappointing.
"I hoped that we would win in Rome and I turned into a supporter for the night. I sat just behind the bench with Gary Neville and a few of the lads who were not in the squad.
"I was shouting and encouraging the lads. We are a team. We got there as a team and I wanted to win it as a team. The 11 on the pitch would have taken the plaudits had we won, but it was a squad effort to get there and players, including myself, made sacrifices to help us get there.
"Now we want to get there again and win this time."