Inter decided not to use their option to buy Keita, who returned to Monaco and made 29 appearances last season.
However, the Fiorentina option intrigues Keita most, according to Di Marzio.
First contacts have taken place between Fiorentina and Monaco and could soon evolve into full negotiations.
Fiorentina will ask for Keita on loan with an option to buy, the same formula that Inter and Monaco agreed on.
Keita scored eight goals and delivered four assists in all competitions for Monaco last season.