The fullback has spent this season on-loan with Inter Milan.
“The two clubs have not reached an agreement, we are waiting," said Mario Giuffredi.
"There is a contractual problem with La Viola. The boy has a contract signed three years ago when he had a completely different value to that of today.
"Cristiano would gladly return to Fiorentina, however, a player of his level cannot remain with a similar contract."