During his second outing for the Nerazzurri since a club-record move from Manchester United at the start of August, Lukaku was presented with the chance to score his second goal of the season from the penalty spot.
The Belgian striker scored from 12 yards to give Inter a 2-1 win at Cagliari but was subjected to monkey chants from a section of the home crowd before and after the spot-kick.
Lukaku called on football's governing bodies to do more to combat racism after the match , while also urging his colleagues to help "unify" against discrimination.
Cagliari are no strangers to allegations of racist abuse, with the likes of Sulley Muntari, Blaise Matuidi and Moise Kean also victimised in recent years.
However, Inter's Curva Nord faction has defended the actions of Rossoblu supporters, writing directly to Lukaku to outline their own perception of racism .
The 34-year-old responded to Curva Nord's comments on Twitter: "And here's the reason why I decided not to play there when I could... And at that point, I wish all the black players would get out of this league! Surely it won't stop their stupidity and hate but at least they won't affect other races."
And here's the reason why I decided not to play there when I could... And at that point I wish all the black players would get out of this league! Surely it won't stop their stupidity and hate but at least they won't affect other races. https://t.co/whu1XexYmy— Demba Ba (@dembabafoot) September 4, 2019
Racism has also been prevalent in the Premier League at the start of the 2019-20 season, with Chelsea's Kurt Zouma targeted by fans on social media along with Manchester United duo Marcus Rashford and Paul Pogba.
Twitter and Facebook agreed to meet with United officials and anti-racism organisation Kick It Out after hateful messages were directed at Pogba, with a discussion set to take place on how best to tackle racism online in the future.
Chelsea striker Tammy Abraham was also singled out by a group of fans after missing a decisive penalty in a shootout defeat against Liverpool in the UEFA Super Cup final on August 14.
Blues boss Frank Lampard has encouraged social media platforms to put a better policing system in place, insisting it is "far too easy" for supporters to "spout hate" online .