Cassano is currently recovering from heart surgery and there was hope that the 29-year-old would return in time for some of Milan's remaining games at the end of the season.
"I have to wait six months to play," Cassano said in an interview with Staffelli Valerio.
"Until then, walk, walk, walk."
Italy coach Cesare Prandelli is keen on taking the striker to Euro 2012 but only if he is fit enough to play a role in helping the Italians navigate a tough looking Group C.
Italy were drawn against reigning World and European champions Spain, as well as Croatia and the Republic of Ireland.
Cassano is unlikely to be fit for the start of Euro 2012 in June, although the Italian appeared in good spirits as he talked about the support he has received since falling in October, and in particular from team-mate Zlatan Ibrahimovic.
"[Zlatan] is one of my best friends," he said.
"I have a great relationship with him and with all of Milan."
Meanwhile, Rossoneri vice president Adriano Galliani insists striker Alexandre Pato is not leaving AC Milan for Paris St Germain.