Napoli have accused Juventus midfielder Claudio Marchisio of insulting them and "all of Italian football".
Partenopei responded to comments that appeared in the Corriere della Sera, in which the Italian international hinted that he 'disliked' Napoli.
"When I am faced with Napoli, something goes off in me," said Marchisio.
Walter Mazzarri's men famously refused to collect their runner-up medals following a heated Italian Super Cup confrontation in Beijing, which they lost 4-2.
That came after a tumultuous 2-0 win in the Coppa Italia Final in May.
"Marchisio's comments represent a grave insult towards Napoli and all of Italian football," said a statement from Napoli. "We are surprised that a player of his stature, who plays at such a prestigious club, would say things like that.
"We hope it is only a misunderstanding and await clarification from the player and from Juventus."
However, the Bianconeri have insisted that Marchisio's comments were tongue in cheek.
"This opinion was clearly referring to the healthy sense of competition that has seen Napoli and Juventus take part in fiery and spectacular matches," said a statement from Juventus.
"There was no offence: failing to comprehend that means trying to create controversy out of nothing."
Juve are currently top of Serie A.
