The teenager was subject to racist taunts from the crowd during the game when Juve travelled to the Sardinian club for the Serie A clash in April.
He held his arms out after scoring Juve’s second as they won the match 2-0.
The celebration appeared to be in reaction to the chants and he was then subjected to further abuse.
His team-mate Blaise Matuidi threatened to walk off during the match as he was also on the receiving end of abuse.
Serie A released a statement on Tuesday saying it had decided not to sanction Cagliari over the incident.
“The chants, even if they were reprehensible, objectively had a limited relevance to the game, even considering the perception,” the statement read. “The decision is not to apply sanctions to Cagliari.”