The former Brazil international believes the Partenopei cannot afford to lose their star player and has singled out Leandro Damiao as the perfect replacement if he leaves
The Stadio San Paolo side recently turned down an offer from Chelsea for the 26-year-old, while the attacker's mother claimed that he is in talks with City and Madrid over a summer move.
Nevertheless, Careca, who wore the Napoli jersey from 1987 until 1993, has urged his former team not to sell as he believes Cavani is too important to the team.
"From all the attackers at the Confederations Cup, I like Cavani the most. He has shown over the past three years that he can score all kinds of goals. He is fast, strong, a real beast," the Brazilian told Corriere dello Sport.
"It's quite simple for Napoli, they should not let Cavani go. The team would lose 70 per cent of its strength if he were to leave. He scores too many goals and is always decisive."
The prolific attacker has a €63 million release clause in his contract with Napoli, which runs until 2017, and Careca realises that there is a chance Napoli cannot prevent their star player from leaving and advised them to go for Leandro Damiao if Cavani indeed moves on.
"I already alerted Napoli to Damiao some three years ago. There's a lot of talk about him possibly moving to Napoli now. He is a very potent striker who is very clever and has excellent technique."
The 23-year-old Damiao has also been heavily linked with Tottenham and Olympique de Marseille in the past few weeks. His contract with Internacional runs until 2017.