Federal prosecutor Stefano Palazzi has also suggested that a three-year suspension for their ex-shot-stopper Matteo Gianello, at the centre of the accusations, would be fair
The accusations revolve around the fixture between Sampdoria and the Partenopei on May 16, 2010, which the Blucerchiati won 1-0 to seal their place in the following season's Champions League play-offs.
However, it is believed that former reserve goalkeeper Matteo Gianello had asked the pair of defenders to participate in an attempt to fix the match, only for the request to be turned down.
"Gianello's proposal on Cannavaro and Grava refers to someone who reported, in confidence, acts of criminal activity," the 51-year-old said in his indictment on Monday.
"For him, there was also the trial, so why did he need to make these statements? Napoli had no goals to be achieved, so it makes it all the more plausible.
"It is not true that we have multiple versions [of his statement]. There is a full transcript of Gianello, who confesses both his and Grava and Cannavaro's misconduct."
Gianello, who left Napoli last summer, had originally agreed a plea bargain with Palazzi so he would only sit out 16 months, but the Disciplinary Committee of the Italian Football Federation (FIGC) rejected the pact.
Palazzi has since revised his demands and now wants the former Siena and Chievo glovesman to be banned for three years and three months for both sporting fraud and his knowledge of criminal contacts.
"The prosecution calls Gianello to be sentenced to a suspension of three years and three months," he added.
"For Cannavaro, it is different given his role and his steadfast refusal [to report match-fixing] by a person implicated by the proposal.
"Still, it is clear that he should be banned for nine months, as should Grava. For Napoli, in relation to its players' [misconduct], they should incur a point penalty this season and a €100,000 (£80,000) fine."