The 31-year-old - reportedly wanted by Harry Redknapp at Tottenham Hotspur - faces an uncertain future at Eastlands following the arrival of several new faces this summer.
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And the Welshman could be pushed further down the pecking order if Mancini completes his chase for Inter Milan striker Mario Balotelli.
Bellamy has been linked with a moves to Spurs and Wolfsburg this summer, but has admitted that retirement is an option he is considering.
"I feel strongly that I can offer something at the club but if I don't get in the 25-man squad, I don't know what I will do," said the Welsh skipper. "I might finish, full stop, or look at every option I get.
"This game is as ruthless as any. I sort of feel I am not going to be part of it [at Manchester City]. I can see it from a distance.
"I find that very difficult to take because I really enjoy playing for Manchester City. I think I have shown that with my commitment this year."
Bellamy revealed the only concrete offer this summer came from German team Wolfsburg, managed by former England boss Steve McClaren, and the Welshman admits he does not know what his next move will be.
"I've had a few options. I've turned down Wolfsburg. I don't fancy Germany, it's not somewhere I see myself playing football. I have to see what options I have. I am here to play football.
"With this 25-man ruling, it doesn't matter how well I train or how good my attitude is, I might not be registered to play. So do I go without playing football until January, or do I find myself a club where I can play football?
"I am committed to stay where I am. I feel I deserve to be part of it, but I don't pick the 25 or the team. I have to wait on their decision."
Spurs boss Redknapp has been monitoring Bellamy's situation with great interest over the summer and is thought to be plotting a move to take him to White Hart Lane on loan should his situation deteriorate further.
The Tottenham boss has struggled to recruit new faces ahead of Spurs' debut appearance in the Champions League, with the likes of Luis Fabiano and Klaas-Jan Huntelaar linked with the club.
To date, Spurs have only signed Brazilian midfielder Sandro - who still cannot join Tottenham after his current club Internacional reached the final of the Copa Libertadores - with Croatian goalkeeper Stipe Pletikosa believed to be close to joining.
Clubs are due to register their 25-man squads with the Premier League before the September 1 deadline at 5pm.
By James Martini
