Belgian Lukaku, 26, was targeted by monkey chants before scoring the winning penalty that earned Inter Milan a 2-1 triumph in Sardinia on September 1.
But the FIGC’s sports judges ruled that reports of “chants, shouts, whistles and screams” from the home fans’ ‘Curva Nord’ (North Stand) just before Lukaku’s penalty could not be considered discriminatory in terms of “size and real perception”.
“The sport judge has decided not to apply sanctions against Cagliari,” the sports judges ruled.
After scoring the penalty, Lukaku made a post-match plea for football authorities to unite against the blight of racism.
Everton’s Moise Kean suffered similar taunts while playing for Juventus at Cagliari’s Sardegna Arena, alongside teammate Blaise Matuidi, after he scored a goal there for his former team Juventus last April.
Cagliari, who issued a statement after the match condemning the abuse, were however fined €5,000 ($5,500) for fans throwing plastic bottles at officials onto the pitch.