The video was deleted but had already been downloaded by some users and is still circulating on the Internet.
Osimhen reacted by removing all the photos of him in a Napoli shirt, except one, from his social media accounts, leaving those in which he appears in Nigeria’s colours.
The forward’s agent Roberto Calenda said the post had caused serious damage to the player and said legal action was being considered.
Napoli have made a shaky start to their Serie A title defence under new coach Rudi Garcia.
Osimhen, 24, did not take being subbed in the closing stages of the Bologna match well.
ANSA