The veteran centre back expressed his distaste at the prospect of the Brazilian returning to the San Siro, claiming that he "stabbed in him the back" when they worked together.
"I helped him out a lot, but after he stabbed me in the back two or three times, I uncovered him," he wrote on Twitter.
When asked how he would feel if Leonardo was to return to Inter, he added: "Over my dead body! We are very different. I am real, he isn't... Besides I love Inter, he doesn't... It's not a small detail, you know.
"I said the exact same things to his face. I never talk about someone behind their back. Never!"
Materazzi, who spent a season in the Premier League with Everton, played for Inter for 10 years, between 2001 and 2011.