Cassano was unimpressed by Real's 5-2 Supercopa final defeat to Barcelona on Sunday.
"If Wojciech Szczesny hadn't been sent off, the match would have ended 10-1. I repeat, 10-1. And not 10-2, because the goal was scored from the foul that followed the sending off," said the 42-year-old.
Despite his Real Madrid past, Cassano did not hesitate to praise Hansi Flick's Barça: "The thing that drives me crazy about Barcelona is their style.
"For them, victory means people always enjoying themselves."
Cassano also said, "Perhaps I could have made more sacrifices for Barcelona... but the most important club in history (Real Madrid) called me with the Galácticos, and I don't regret anything.
"But looking back, knowing what I know now about Barcelona, if I'd had the chance... At that time they had Ronaldinho in my position and Barça never came looking for me, they had the Ballon d'Or.
"I fell in love with Barcelona and I still do."