City won 2-0 against Bayern Munich at home on Wednesday, but Napoli secured progress to the last 16 following their victory at Villarreal.
“No, we have not really (enjoyed the Champions League campaign) because we have not done what we wanted to do,” he told Sky Sports.
“We are a good side and we should be doing better in his competition.
“But naiveté and a few bad performances and you are out, and that is the brutality of the Champions League.”
