Lukaku was sanctioned with a second yellow card for provoking Juventus fans by holding his finger to his lips as if to silence the crowd after converting a stoppage-time penalty to earn Inter a 1-1 draw in the first leg of the semi-finals on Tuesday.
The Belgian striker was suspended for the second leg of the semi-finals on April 26 by the Italian league judge on Thursday.
Lukaku's gesture enraged the opposing team and the game ended in a scuffle between the two squads, with Juventus winger Juan Cuadrado and Inter goalkeeper Samir Handanovic also sent off.
Cuadrado was banned for three matches while Handanovic was banned for one game. Each player was fined 10,000 euros (A$16,000).
Part of the southern end of the Allianz Stadium will be closed for Juve's first home game in next season's Italian Cup.
Juventus said it would collaborate with authorities to identify the fans responsible, while Lukaku's management company reacted with outrage to the yellow card handed to the centre forward.
"The Italian authorities must use this opportunity to tackle racism, rather than punish the victim of the abuse," Roc Nation Sports International president Michael Yormark said.
Lukaku has been subjected to racist chants on numerous occasions during his two stints at Inter.
The incident involving Lukaku comes amid an uptick in racism in European soccer following a lull during the coronavirus pandemic.
Also on Thursday, Leipzig defender Benjamin Henrichs published hateful messages, including racist abuse, that he had received on Instagram following his team's 2-0 win over Borussia Dortmund in the German Cup.
Henrichs posted a video on TikTok in which he referred to Wednesday's victory and says "I'll show you what my DMs look like," before displaying a series of messages of threats and abuse against him and his family.
One message had only monkey emojis, another called him the N-word, while another threatened to "find you and your family."
Back in Italy, Lazio were also given a suspended partial stadium ban this week after some of their fans directed anti-semitic chants at Roma during the city derby last month.
The Serie A judge ordered the Curva Nord, the northern end of the Stadio Olimpico where Lazio's hard-core "ultra" fans sit, to be closed for a game, but suspended the sentence in consideration of Lazio's decision to hand out three lifetime bans to involved spectators.
On Tuesday in Spain, Real Madrid forward Vinícius Junior testified against a Mallorca fan accused of racially insulting him at a Spanish league game, saying he would not accept an apology.
AAP
