The UEFA Champions League clash at San Siro - which ended in a goalless draw, enough to see Milan through to the last 16 - was marred by clashes between rival fans before the match.
According to reports, three Ajax fans were taken to hospital with stab wounds sustained during an incident before the match.
The violent attacks are alleged to have been a response to fighting earlier in the day involving Ajax fans and locals, and Berlusconi - the daughter of club president Silvio - was disgusted with their actions.
"The satisfaction of reaching the next round is overshadowed by these incidents," Berlusconi said.
"They are serious and unacceptable acts. What has happened today in Milan is extremely serious.
"The people on both sides who have caused these incidents are not football fans but delinquents."
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