Inter won their first home game of the season 2-1.
"Inter earned the victory by limiting the qualities of the opponent, who are very good at controlling the ball," he told Sky Sport Italia.
"I got a little angry because we left the game open despite having numerous chances. We should've killed it off, as a match like this is always full of potential pitfalls."
This was the second outing for the new 3-5-2 system and both have now ended with victories.
"Hitting the bottom of the table was important for us, because it made us understand that we had to change something and go on to the field with a different attitude.
"Tonight we exhibited determination and hard work. It was a show of strength and of quality, above all because Fiorentina are such a dangerous side."