The victory in Florence was decided by two late goals from Klaas-Jan Huntelaar and Alexandre Pato.
Riccardo Montolivo in the box.
The referee gave the advantage because the ball fell to Keirrison, whose shot was parried at point-blank range by Christian Abbiati.
"In all honesty, I have heard the opinions of many people involved and must admit Fiorentina deserved a penalty," confessed Leonardo.
"However, the referee clearly played the advantage. The foul on Montolivo was there, but Roberto Rosetti let play continue because Keirrison had the ball."
"We struggled a great deal in the first half with a Fiorentina side that started well. The Viola were piling on the pressure and our midfielders had no space.
"After the break with character and hunger we managed to bring home the result. Aside from tactics, it was spirit that got us this victory.
"Abbiati, Ronaldinho and Pato were decisive, but Mathieu Flamini also played a great game."