City boss Roberto Mancini admitted last week that Cerci could be an option as he looks to bolster his squad for Champions League football this season, as well as a potential challenge for the Premier League title.
Cerci has emerged as a highly-rated winger, scoring seven goals in 24 Serie A games for Fiorentina since joining from Roma last summer.
And Corvino insists the Viola have turned down a concrete approach for their 24-year-old star from the big-spending Blues.
"The only offer we have received is that of Manchester City for Cerci but the proposal didn't satisfy us," said Corvino.
"Cerci is an important player for us. He didn't ask to leave and we have no plans to sell off our players."