AC Milan coach Carlo Ancelotti expressed his shock at the crowd trouble which forced the abandonment of their quarter-final tie with Inter.
"Tonight's episode doesn't just hurt Inter, but the entire city of Milan," said Ancelotti.
"The reaction of the Inter fans was surprising. I've played and coached in Milan for 10 years and I've never seen anything like it."
Milan goalkeeper Dida was hit by a flare but was not badly injured.
However, his team-mate Clarence Seedorf added: "He does have some pain where he was hit."
Milan were leading 1-0 and looked set to advance 3-0 on aggregate when the game was stopped in the 73rd minute.
Inter fans reacted angrily to referee Markus Merk's decision to disallow what appeared a legitimate goal by Esteban Cambiasso and started to launch missiles onto the field.
"After the goal was annulled, the fans' anger was understandable," said Inter defender Ivan Cordoba.
"Although the reaction of throwing objects onto the field is not justified.
"We can't say anything to the fans tonight. We didn't give them the satisfaction they were expecting."
Merk called off the match when more fireworks were thrown as he tried to restart play.
The scene at San Siro stadium followed one of the worst violence-marred weekends in Italian league play this season.
Scores of fans were arrested throughout Italy after confrontations with police.
In September, Swedish referee Anders Frisk was hit in the face and bloodied by an object thrown from the stands in Rome during a Champions League match between AS Roma and Dynamo Kiev.
Roma received a two-match home fan ban for that incident.
"The government, the entire country, has to understand that something must be done," said Seedorf.