The Netherlands international is under contract at the Allianz Stadium until June 2024, but is yet to agree an extension with the Bianconeri.
Chelsea has been linked with a move for the 22 year-old, who has a release clause of €125million.
De Ligt has been a regular in the heart of the Juve defence since arriving from Ajax for €85.5million in 2019.
The centre-half has racked up 117 appearances across all competitions, scoring eight goals, and winning the Serie A title during his maiden season with the Old Lady.
Ferrara, who won five Scudettos and the Champions League with Juve between 1994 and 2005, acknowledged De Ligt's importance, but insists the club should not stand in his way.
The former defender told Tutti Convocati: "We have to understand if De Ligt has the right motivation.
"He is an important figure in the defence. But if he wants to leave, then Juve will not hold him against his will."