This season's campaign is all but over ahead of their home clash with Ajax.
"I don't think that we are ready to win the Champions League," Mancini said. "If we say this, we are not honest.
"We are a good team. We are not ready like the other teams.
"Chelsea tried for 10 years to win the Champions League. They were probably the best team in Europe for 10 years and they won it after 10 years, probably when they didn't deserve to.
"They deserved to win it three or four years before. The Champions League is like this.
"If we are very good, we are fantastic, we win the next three games, everything can happen. But, before, the way is very long."