Sunday's game was stopped for 97 seconds during the second half when visiting Roma supporters would not stop chanting at Milan players Mario Balotelli and Kevin-Prince Boateng. The league fined Roma 50,000 Euros, equivalent to almost $65,000, on Monday.
"Appalled to read about racist abuse in Serie A last night," Blatter tweeted Monday. "Tackling this issue is complex, but we're committed to action, not just words."
Blatter added that FIFA's taskforce against racism and discrimination is "serious about devising a unified approach for FIFA's 209 members."
Referee Gianluca Rocchi made the decision to suspend the match briefly after warnings issued over the stadium speaker system went unheeded. Roma captain Francesco Totti had also attempted to calm the fans to no avail.
Balotelli was born in Italy to Ghanian immigrants and is the star forward of Italy's national squad. Boateng was born in Germany to a German mother and a Ghanian father and plays for Ghana's national team.
The match at Milan's San Siro stadium ended 0-0.
Roma general director Franco Baldini said it was uncertain whether the chants were racist.
"The boos were directed at Balotelli because he's a feared player," Baldini said, according to the Gazzetta dello Sport. "The nature of the chants was not clear. And I clearly heard the Milan fans chanting 'romano bastardo' - 'roman bastard' - which is just as discriminatory. It's difficult to figure out where the border is between racial discrimination or simple boos."
This was the first time a Serie A match was suspended due to racism.
In January, Boateng famously walked off the field with his teammates after enduring racist abuse during an exhibition against a fourth-tier Italian club.
"The perception is still that in certain areas of the stadium you can do anything," Italian players' association president Damiano Tommasi said. "It's important to make those people feel more and more in the minority.
"The goal is to make people who behave poorly leave the stadium, although that's not simple for reasons of public safety," Tommasi added. "It's always a very fine line between penalizing the majority of people who go to the stadium to enjoy the show and punishing the minority who ruin it. It's not simple but it seems to me that yesterday everyone was in agreement with Rocchi's decision."