Italy will take on Bulgaria and Malta over the course of the next eight day.
"Cassano has said that he is currently only at 50-60 per cent and, at this moment, I don't have time to recover players because we need to win games to qualify," Prandelli said.
"He just has to re-find his form, then there will only be tactical decisions to make.
"I can't take any risks in these qualifying games with players who are not in perfect physical condition. There is a lot at stake here.