Former Ferrari boss Stefano Domenicali has tipped Sebastian Vettel to "behave correctly" during the 2020 season.
"The tension won't help anyone - not even Leclerc," Villeneuve told La Gazzetta dello Sport.
"Leclerc knows he is the team leader now but he is still against a four-time world champion. Charles has the potential to manage it, so we will see how he does."
Domenicali, who stepped down as Ferrari boss in 2014, backs the Maranello team's decision to push Leclerc to the top of the hierarchy.
"Yes, because he has enormous talent," the Italian told Il Resto del Carlino newspaper. "His development also reinforces the idea of the academy that we launched for young drivers."
Domenicali said drivers like Leclerc and Max Verstappen "are the symbols of the new generation".
"As for the contractual dynamics (at Ferrari), I don't judge it but I do know that Seb is a professional. Whatever his future is, he will behave correctly."
Vettel will leave at the end of 2020, to be replaced by Spaniard Carlos Sainz.
Villeneuve said: "Sainz is not Verstappen, but he is a strong driver.
"He will not bother the other driver, instead they want another Schumacher-Barrichello situation, as Sainz has more of a Barrichello name and image."