The manager was disappointed with the manner in which his side exited Europe after a tame showing at Stamford Bridge.
Roberto Mancini labeled Galatasaray's showing in its 2-0 Champions League last-16 defeat at Chelsea on Tuesday as "very, very bad."
After drawing the first leg 1-1 in Turkey, the Istanbul club knew it had to score at least once to have any chance of progressing to the quarter-finals, but they put in a limp display at Stamford Bridge.
Even striker Didier Drogba, the subject of much of the talk in the buildup ahead of his return to his former club, failed to cause any problems for the home defense as first-half goals from Samuel Eto'o and Gary Cahill saw Chelsea through 3-1 on aggregate.
"We really played very, very badly," he said after the match. "Chelsea were the better side and they converted the opportunities they got. It’s impossible to score with just one shot on goal. We need to take several steps in order to be a better team."
Drogba, meanwhile, was disappointed with his side's inability to match its first-leg performance.
"We wanted to play the way we played in the first leg but that did not happen," the Ivorian striker said. "We are still learning and the team is still young. I hope next season things will be different."