Although Arsenal manager Arsene Wenger has insisted Nasri, who has only 12 months remaining on his contract, will still be at the Emirates next term, Mancini is determined to push through the transfer.
Arsenal are well aware that if they do not sell Nasri during the current transfer window they could lose one of their star players for nothing next summer. And with City reportedly prepared to pay £27 million to land the France international it is an offer the North London club will find hard to resist.
Mancini told Sky Sports News: "Samir is under contract with Arsenal. Also for Samir it depends on many things.
"I don't know in this moment, I don't know the situation but for Nasri it is difficult.
"I hope that we can buy because we need other players, and I hope that this player can arrive before the end of the month.''
Mancini has also set his sights set on Atletico Madrid striker Aguero after City received an improved £40 million bid for Carlos Tevez from Brazilian club Corinthians.
City turned down a £35 million bid for the Argentina international earlier this week and are thought to be holding out for £50 million, but Mancini appears resigned to losing his skipper in turning his attentions to Aguero.
Despite Corinthians claiming Juventus had made a formal offer for Tevez, Manchester City insist they have not received any formal bids for the striker from any European clubs. Tevez, who played for Corinthians before moving to West Ham in 2006, is keen to return to Brazil.
If City accept Corinthians' final bid, Mancini is likely to pursue Tevez's international team-mate Aguero, who has made it clear he does not want to stay at Atletico. "Aguero is a player that can play for Manchester City because he is young and he is a good player like Carlos," Mancini said. "He can score a lot of goals and can play with Mario [Balotelli], with Edin [Dzeko]...it could be [possible]."