So far this month, City have failed to add to their squad ahead of their Premier League title run-in with Manchester United, while Mario Balotelli is on the verge of a return to Italy.
When asked whether he will sign players this month, Mancini replied: "I don't know but we don't have enough players. It is difficult [to bring any in]. We are 18 players now. We can't sell any players."
Goal.com revealed that Balotelli has given notice on his Cheshire home as he prepares for a move back to AC Milan, although Mancini wants the striker to stay and earn his place at City.
"Mario should work well and try to get his place in the team because at the moment he doesn't play – for many reasons," Mancini said.
"I hope he can help us to win some trophies because he has the quality. I think today his performance is so-so but at the same time he can improve because in next four months we have important and crucial games."
Mancini dismissed claims that he could be tempted into fielding a weakened team against Stoke City in the FA Cup on Saturday, a match that sees a repeat of the 2011 final that City won.
"In Italy we used to do this," he added. "In England the FA Cup is more important. I understand some teams think about staying in Premier League.
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|5/2||Man City are 5/2 with Bet365 to retain their Premier League title this season|
"I will always play my strongest team. When you play on a Saturday it is okay. It is difficult to win one trophy, to win a Double is hard but we will try.
"Stoke at home is a different team. Very difficult for every team they meet but if we play football we can have a chance to win.
"It is not only for us. Every team that goes to the Britannia has a problem because Stoke at home is strong – play well, physical, set pieces. But the last two years we played well and had a lot of chances to win and were really unlucky.
"The pitch is smaller than the Etihad Stadium and probably they have a different approach to the game. There are sometimes some squads that play very strong at home and away are different. Stoke are like this."