The 30-year-old explained why he was not sat alongside his team-mates and remains determined to stay at Old Trafford next season.
"I will stay," Berbatov told Bulgarian television. "I will fight for the 20th title.
"If I were an easy quitter, I would never have made it this far. Everything at Manchester United starts from scratch for me on July 4.
"There will be new finals and we will be fighting for new titles. I am moving ahead. When you go through difficult times, you should not quit.
"The truth is that I stayed at the dressing room and watched the Champions League final there, on a TV screen.
"I was really disappointed. I was ashamed that I was not part of the team and did not want people to see how sad I feel."