Aquilani’s future has long been in doubt, with the Turin club so far failing to offer the player a permanent contract and allegedly stalling negotiations with the Premier League side in order to reduce their asking price.
Zavaglia told Italian radio station Mana Mana that the player’s future was entirely in the hands of the Juventus board and that all the details had been arranged.
He said: "The agreement is, by June 30, Juventus will have to pay €16 million [£13.9m], established in the summer. There is an expiration date, everything is organised.
"Only the Juventus team can lose. What has been done does not provide for further negotiations."
Zavaglia appeared confident Aquilani would stay in Italy and with all probability sign on with the beleaguered Turin outfit, but he refused to rule out a return to his hometown club, Roma.
"[Aquilani] will stay at Juventus," he stated. "I believe there are no obstacles in this regard. Aquilani is not a player to be put into question.
"Juventus has a right of first refusal. I do not think [a return to Roma] is possible, but in football nothing is obvious."