The Colombian has expressed a desire to move to Turin but the Bianconeri say they do not want to ruin their relationship with Napoli in order to make it happen
The Bianconeri have been linked with the Colombia international all summer and the 27-year-old, who has just 12 months remaining on his contract with the Partenopei, admitted earlier this month that he would welcome a move to Turin.
Marotta has now admitted that the Italian champions are keen to do a deal, but not at the risk of ruining their good relationship with Napoli.
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"We're talking about an important player in [Rafael] Benitez's squad, so I'm afraid it will be difficult to take him away.
"We, given the good relations between the two clubs, do not intend to interfere."
Despite their interest in recruiting Zuniga, Marotta insists that Juve have no intention of selling Mauricio Isla, who is currently being courted by Inter.
"Isla will not move from Turin," he declared. "There was involvement from one club, but we said no.
"We have [Simone] Pepe, whom we are re-integrating back into the squad [after injury] and we will count on him."
Marotta did admit, however, that both Alessandro Matri and Fabio Quagliarella will be allowed to leave should they so desire.
"Juve are a top club and any player would have a hard time saying goodbye," he explained. "In effect, though, we have six strikers, and that perhaps that is too many.
"However, for Matri and Quagliarella, much will depend on their own decisions."
Juventus kicked off the defence of their Serie A title with a 1-0 victory away to Sampdoria on Saturday evening, with recent arrival Carlos Tevez scoring the only goal of the game.