The 25-year-old collapsed during Livorno's Serie B clash with Pescara.
"He was an absolutely lovely lad. I was shocked when I heard," said Balotelli. "I couldn't believe it and hoped it was just some horrible prank.
"This makes me reflect on many things in my life. It teaches me to appreciate life, respect it and experience it with caution and dignity."
Morosini was on loan at Livorno from Serie A side Udinese.