Last week, during the second leg of the Coppa Italia semi-final at San Siro, the travelling fans targeted both players with racial chants which the Italian league's disciplinary tribunal said could be heard “by everyone” in the stadium.
Lazio have, however, escaped an immediate closure of the Olympic Stadium but would be punished if found guilty again within the next 12 months.
The visitors went ahead to grab a 1-0 victory to book a date with Atalanta in the final of the competition.
After the encounter, Milan sporting director Leonardo Araujo was infuriated with the way the incident was handled, questioning why the match was continued in such hostile condition.
"There were one thousand reasons to stop the game," Araujo told Gazzetta dello Sport.
"With the new rules, there is no need to wait for the second or third round of chants, the first is enough to take the teams to the middle of the pitch and make an announcement.
"In the case of more chanting, the match should be stopped indefinitely. But nothing happened. Everyone heard the racial insults and the monkey noises."