The Italian coach is confident about the striker's chances of playing in Poland and Ukraine, while expressing surprise at Juventus' criticism of referees lately
The Italy international has been out of action since undergoing heart surgery in November after suffering a mini-stroke on the club's flight back from a match in Rome.
There have been conflicting reports on Cassano's recovery time, with Italy coach Cesare Prandelli stating last month that the striker is working hard to regain match sharpness to be available for the European Championships.
Allegri believes that 29-year-old will be able to help the club in the last matches of the season, which should increase the striker's chances of making Prandelli's squad for Poland and Ukraine.
"We hope to have him back by the end of the season," Allegri is quoted by La Gazzetta dello Sport as saying. "For us and for the Italy national team.
"Antonio was having the best year of his career in terms of physical and technical levels.
"Prandelli has been doing a good job and we hope to give him Cassano. It would be an important boost for us and Italy."
The 44-year-old coach then criticised Juventus' decision to enforce a media blackout and reminded how Milan were wrongly denied a goal in the 1-1 draw against the Bianconeri last month.
"It was a bad decision, but it is part of the game," Allegri added. "[Sulley] Muntari's goal was very clear, but Juventus are still debating whether [Simone] Pepe's goal was offside or not.
"After the matches, we have to discuss technical and tactical matters, not the officials' decisions.
"There is no tension on our part, but I see that many are putting together dossiers and no one is discussing the decisions which favoured Juventus.
"It is clear that what happened with Muntari took place in an important match, but we hope that it will not be decisive in the Scudetto race."