The Rossoneri had an offer believed to be in the region of £6m rejected by Fiorentina last week, with La Viola branding the bid "unacceptable" in an official club statement.
"All we have done is made an offer during the transfer window," Football Italia quotes Galliani as saying. "We haven't done anything wrong.
"At this moment in time, the conditions are not in place to complete the deal."
Ljajic, who has less than 12 months to run on his contract in Florence, scored 11 times in Serie A last season, helping Vincenzo Montella's side secure Europa League qualification by finishing fourth.