Former goalkeeper Mattia Gianello reportedly approached Paolo Cannavaro and Gianluca Grava in an attempt to fix the result of a game against Sampdoria in 2010, and the club have been docked two points and fined €70,000 [£57,000] for not reporting the incident.
Cannavaro and Grava have also been banned for six months, but the club does not believe they should have been punished.
"The president Aurelio De Laurentiis, the coach Walter Mazzarri and the the whole team are confident that no violation can be attributed to SSC Napoli," read an official statement on the club's website.
"While not entering into the obsolete and outdated principle of objective responsibility and reserving any comments and any legal action, SSC Napoli does not agree with the decision of the National Disciplinary Committee.
"Any decision must be made before the start of the season or at the end of it. Since the date of this incident there has been time to evaluate and decide."We are confident that in the two degrees of judgement, we will be warranted true justice."
The points deduction has left the Stadio San Paolo outfit 10 points behind Serie A leaders Juventus as they look to win their first league title since 1990.