The Real Madrid coach is under pressure in Spain and could be on the move at the end of the season.
Sacchi says Milan's owners should recognise the opportunity and seek to bring Ancelotti back to the club.
“What makes me sad, even if this is part of football, is that everyone is criticising Carletto because of a Champions League exit and blaming him for the elimination,” Sacchi told La Gazzetta dello Sport.
“Do these people have any idea who Ancelotti is? Do they know what he has won? I consider him a real master of the game, not just because of the trophies, but also for his human qualities.
"Real Madrid should think not once, but twice or three times, before letting go of someone like Carletto."
Serie A return?
He added, “I don’t know what Carletto wants to do. Apparently, the Brazilian federation has been after him for a while now, and surely the chance to coach the Seleçao at the World Cup is tempting.
“In any case, I’d give Carletto a call if I were at Milan or Roma, it doesn’t cost anything. I don’t know if the dream will come true. For now, let’s just keep dreaming.”