Previous reports suggested the 24-year-old was edging nearer to his much-speculated City move, and Mancini has hinted that the deal should be completed soon.
"I hope we can close it very quickly now, but I don't know the last news about him because my concentration is on the game," said Mancini. "But I hope - also because the market finishes in the next 10 days."
When asked why negotiations had been delayed, the Italian added: "I don't know - this is not my job. I don't know why, but it is probably because Nasri is a good player, or because there is some problem."
Meanwhile, City are preparing for their away fixture at the Reebok Stadium against Bolton on Sunday.