Play was stopped for almost two minutes during the second half of Sunday's game when visiting Roma supporters would not stop chanting at Milan players Mario Balotelli and Kevin-Prince Boateng.
Warnings issued over the stadium speaker system went unheeded, leading to a Serie A match being suspended due to racism for the first time.
FIFA President Sepp Blatter has put renewed vigor into the fight against racism since Milan midfielder Kevin-Prince Boateng led his teammates off the pitch when he was racially abused during an exhibition game against an Italian fourth-tier side in January.
Blatter is unhappy that the latest case was so quickly wrapped up by Italian soccer officials, while branding "small fines for racist abuse unacceptable."
"What is surprising and is not understandable for me, is that the disciplinary committee of the Italian Football Federation has taken a decision, not even 24 hours after the event, by just imposing a fine," Blatter said Tuesday on FIFA's website. "They have not made any investigation of what happened. And just to give a pecuniary sanction is not valid, that is not acceptable. You will always find money.
"What is 50,000 euros for such an incident? I'm not happy and I will call the Italian Federation. That's not a way to deal with such matters.
The Boateng incident in January followed a spate of racial-abuse cases in England and prompted Blatter to establish a task force to propose stricter sanctions.
In plans being presented to the FIFA Congress later this month, teams face being thrown out of competitions or even relegated if their players, officials or fans are found guilty of any form of discrimination.
"In this resolution, there are foreseen sanctions—and these sanctions must be applied all around the world," Blatter said. "That's why we need the congress's decision. That will bind together all the 209 associations.
"I'm looking forward to that and I do hope, that there we will be no other incidents until the 30 May, when we will deal with this matter in Mauritius ... I appeal to everybody for a little more discipline and respect."
UEFA, at its congress in London next week, will ask its 53 members to adopt a series of tougher racism sanctions.
UEFA wants a partial stadium closure to be imposed on clubs if there is racism in the stands—rather than just a fine for a racist offense. If there are further incidents, UEFA is advocating clubs being forced to play matches behind closed doors.
A 10-game minimum ban for players found guilty of racist abuse is also being proposed.
The English Football Association is looking to push through its own plans for a five-game minimum ban for racist abuse at its own annual general meeting this week.
In England in recent years, Liverpool striker Luis Suarez received an eight-match ban for racially abusing an opponent and Chelsea captain John Terry was suspended for four matches.