Despite interest from Premier League big-spenders City and Chelsea, the 26-year-old could be moving to Spain.
"Real Madrid is interested in Edinson, but his release clause is very high, so it's complicated," Cavani's brother Walter Guglielmone told Italian radio.
"I would like to see him play in Spain. Edinson is focused on ending the season in the best way possible. Money isn't important.
"If he had to leave Napoli, people would understand. The city has given him a lot and he has returned that affection.
"Personally, I don't know if he'll stay in Italy, but he's reached the top in the Napoli shirt and is really happy at having scored 101 goals for the club."