With a week to go until the August 31 transfer deadline, Mancini, who has only signed Jack Rodwell since the end of last season, remains hopeful of strengthening his squad and has been linked with a host of new recruits.
The Italian knows England winger Adam Johnson and Bosnia striker Edin Dzeko are interested in leaving City as they look to gain more regular first-team action.
But, after selling Emmanuel Adebayor to Tottenham this week, Mancini insists he cannot let anyone else go until he brings in more fresh faces.
"We have another week. I'm sure we will do what we want next week," Mancini said on Friday.
"We are working, we can't say a name or how many players but we are working in the last 10 days.
"Adam Johnson is a City player at the moment. We can't sell a player if we don't buy other players, because we won't have enough players.
"We can't sell our players if we don't put other players in. We have 19 players at the moment and two or three players injured. It's impossible."
Mancini remained coy on the club's reported bid for Swansea winger Scott Sinclair, but dismissed rumours linking City with an offer for Chelsea defender David Luiz.
The City boss has also ruled out a move for Athletic Bilbao's Javi Martinez, claiming the Spanish side want too much money for the midfielder.
"It's difficult, his cost is too big. It is too high for me," Mancini added.
Mancini is more concerned with how his side fare without star striker Sergio Aguero and was quick to rule the injured star out of international duty with Argentina.
Aguero was called up by Argentina's national side for next month's World Cup qualifiers before suffering a knee injury in City's 3-2 win over Southampton on Sunday.
However, Mancini does not expect his top scorer from last season to be fit before City's league match against Stoke on September 15 and said there is no chance he will play for Argentina before then.
"After the international break he will be ready. He will not go away for the internationals," Mancini said. "It's his knee, it's a bad injury but not for six months (as he had feared). After two weeks he will be able to train."
Aguero's absence has left Carlos Tevez to lead City's attack at Liverpool on Sunday.
Mancini has been impressed by the Argentina striker, who spent most of last season in self-imposed exile after a touchline row with the Italian.
"It's the first time for a long time that he did a pre-season which is very important for every player. For Carlos it's more important because in the last four or five years he did not do a pre-season," Mancini said.
"I hope he can continue to score and play like this. Now it?s important because we lose Sergio for two or three weeks."
Although Liverpool started their season badly last week with a 3-0 defeat at West Bromwich Albion, Mancini surprisingly claimed they are real title contenders this year.
"I think Liverpool will fight for the title this year because they play well, they bought good players," Mancini said. "They got a good manager and they changed their style. They will fight for the title."
Source: AFP
Source: AFP