Ljajic is in the final year of his contract with La Viola and Milan were hoping to take advantage with a cut-price deal.
Fiorentina co-owner Andrea Della Valle has declared that the club are confident of persuading Ljajic to sign a new contract, but will sanction his sale if fresh terms cannot be agreed.
He told reporters at the club's summer training camp in Moena: "From what I know, the offers we have received so far are some way off the player's value. I spoke with the player this morning, he seems calm and expressed his desire to remain in Florence. We'll now meet with his agent next week.
"I hope he stays here with us. He is a future champion who can give a lot to Fiorentina. We are aware of his qualities, but certain evaluations need to be made when talking about salaries. Fiorentina will make their considerations and I hope the player understands our offer.
"If he doesn't accept a new contract, then he will be sold. There will not be another Riccardo Montolivo situation [who left for Milan last year]. I'm relatively optimistic, though."
The 21-year-old helped Vincenzo Montella's side finish fourth in Serie A last season, scoring 11 goals in 28 league appearances in the process.