The Serbia international has been linked with a move to AC Milan this summer but the former Italy striker insists he would be better served by staying at the Artemio Franchi.
"He's experiencing an internal conflict," he told La 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 calm, and today he doesn't look all that calm. I'm still convinced that [staying with Fiorentina] would be the best solution for him."
Meanwhile, sporting director Prade called on the 21-year-old to show that he wanted to stay at the club as he negotiates a new deal.
"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 told Mediaset.
"We are a strong club and we expect the player to tell us what he wants to do.
Finally, Parde also ruled out potential moves for Cagliari duo Radja Nainggolan and Michael Agazzi.
"Nainggolan or Agazzi will not be coming. There are no negotiations for them," he added.