Mancini repeated his mantra that City's problems date back to the summer, when he is adamant they failed to move quickly enough in the transfer market, losing out on Robin van Persie in particular.
"Our target at the start of the season was to try and win the Premier League," he said.
"But our mistake started in the last market. We didn't do enough to improve our team.
"After winning the Premier League, the second year is more difficult.
"Then maybe you don't get the Champions League. You can have a bad season. We had problems because we lost some players. We lost Yaya (Toure) for a month. We had a lot of problems this season.
"Every manager takes the responsibility. That is normal. But I don't think last year, when Manchester United lost the Premier League and didn't play in the FA Cup final they had all the discussion we did."