Juventus are ahead of the Partenopei at the top of the Serie A table by one point with a game in hand and are now in the driving seat for another Scudetto.
After Titti Improta asked Sarri to elaborate on the difficulty of catching Juve, the Napoli boss responded: "You're a woman, you're pretty, for those two reasons I won't tell you to piss off."
Sarri, who is reportedly on Chelsea's radar as a replacement for Antonio Conte, then laughed, though he is reported to have apologised to the journalist in question afterwards.
Ottavio Lucarelli, chief of the local journalists' union, is quoted by The Independent as saying: "It was a sexist and unacceptable response.
"Sarri apologised, but the seriousness of his response remains, which not only underlined the coach's vulgar language also but his contempt for the press and women.
"We're in total solidarity with our colleague Titti Improta, the secretary of the Order of Campania and the President of the Equal Opportunities Committee, who is receiving messages and support from all over Italy at this time."
After the same fixture two years ago, Sarri was fined €20,000 (£17,500) and banned for two Coppa Italia games for "directing extremely insulting epithets at the coach of the opposing team" after allegedly using homophobic language.