The in-demand midfielder is set to move in January and the champions are likely to begin negotiations in an attempt to bring him to Turin
Juve recorded an impressive 4-1 away victory over Atalanta on Sunday, stretching their winning run to nine league games.
Coach Antonio Conte continued his press blackout after the match, so it was Marotta who faced reporters and discussed the prospect of signing Nainggolan next month.
“Nainggolan is a great player and one who is ideal for Conte’s Juventus philosophy,” he said to Sky Italia.
“We do have a good rapport with Cagliari, so we will see what happens.
“His arrival would not mean selling Arturo Vidal. At least for this season, no big names will be leaving us.”
After his side's 1-1 draw with Napoli this weekend, Cagliari president Massimo Cellino said star players Nainggolan and Davide Astori were welcome to leave the club.
AC Milan, Inter and Roma have also been credited in holding an interest in the 25-year-old Belgium international, while a number of clubs from outside Italy – including Manchester United – were linked in the summer.
Marotta was happy with Juve’s performance on Sunday, which ensured they kept their five-point lead over Roma at the top of the table.
He continued: “This is a solid group with real determination. We were already built to win and we have added some important elements to the squad each year.
“I must say Fernando Llorente and Carlos Tevez really made their mark against Atalanta.”
Juve will get the opportunity to make it 10 Serie A wins in a row when they face Roma in a top-of-the-table clash on January 5.