The 21-year-old is reportedly on the radar of a number of Europe's top sides, having starred at the Stadio Artemio Franchi since his arrival from Partizan Belgrade in January 2010.
But Prade is keen for a quick resolution to the matter, and has explained that a new contract is on the table for the Serbia international.
"We are working on a renewal with Ljajic, but he has to prove that he wants to stay. If not, the doors are open," he said.
"We are a strong club and we expect the player to tell us what he wants to do."
And the club's head coach Vincenzo Montella has admitted that the player has appeared distracted by the uncertainty over his future during pre-season training.
"He's experiencing an internal conflict," he told Gazzetta dello Sport. "He has not looked very serene in recent days. What can I say, there are economic problems which are not easy.
"I'm willing to wait, just as long as he's serene, and today he doesn't look all that serene. I'm still convinced that [staying with Fiorentina] would be the best solution for him."
Meanwhile, Parde also ruled out potential moves for Cagliari duo Radja Nainggolan and Michael Agazzi.
"There will be no arrival of Nainggolan or Agazzi. There are no negotiations for them," he added.
Ljajic made 31 appearances for Fiorentina last season, scoring 12 goals.
