The former Inter Milan boss was dismissed on May 13 - the anniversary of the previous season's dramatic Premier League title success - after three days of mounting speculation over his future.
The club declared Mancini, who has since been replaced by Manuel Pellegrini, had "failed to achieve any of its stated targets this year, with the exception of qualification for next season's UEFA Champions League".
Quoted in Italian newspaper Corriere dello Sport today, he said: "Even now, (almost two months) later, I still do not understand why. It is still painful, I admit. I think I deserved more respect for what I had done for Manchester City.
"In three and a half seasons with my staff, I believe I did an extraordinary job.
"The club had not won a (league) title for more than 40 years. I won a championship title, FA Cup, a Community Shield and, in the worst season - the last one - I lost a final and I came second (in the league).
"The numbers are clear. This sacking still does not have a reason.
"The Arabs called me and said to me 'in three years we want the title', and I won it in the second year. And then I rebuilt a club that was not at the top level of football. Evidently, chairman Khaldoon (Al Mubarak) must have had in his head some situations that were not true."
Mancini pointed a particular finger of blame towards chief executive Ferran Soriano, saying: "For him, I was a person too big (within the club). He and I did not speak the same language and I do not mean Italian, Spanish or English."
Mancini's final season at the Etihad Stadium was also notable for the sale of Italy striker Mario Balotelli to AC Milan, seemingly marking the end of a tempestuous relationship between the pair.
The 48-year-old gave Balotelli considerable support during their two and a half years together in Manchester, despite voicing his frustration on numerous occasions - and a training-ground bust-up four weeks before his departure.
"By that time, I understood that in England he was not very well any more," Mancini said. "He - like (Liverpool forward Luis) Suarez - was targeted by opponents, referees, the public.
"Sure, he has not done anything to avoid certain situations.
"I love him, but I have not heard from him since he arrived at Milan."
As for his future, the ex-Lazio coach would be interested in returning to the Italian capital to manage Roma, but stressed he had never been approached by the Serie A outfit.
"We are talking about a great club, with absolute prestige, which is trying to rebuild a cycle," he said. "It's an adventure that would have had its own charm, I do not deny it ... Never say never.
"I would have considered an interesting proposal. I have never had any direct contact, though."