The versatile Argentine has become a key player for Udinese following his 2011 move from River Plate and champions Juve are reported to have agreed a deal that would see Frederik Sorensen move in the other direction.
Giaretta denied that the Turin giants are on the verge of signing Pereyra and stated that they face a battle for his signature.
Giaretta told Fcinternews: "Is it all done with Juve? No, there is no deal yet and I don't want to go one way or the other right now.
"He is a very interesting player, so we're not surprised clubs are eyeing him up. As nothing is confirmed yet, the issue is still wide open.
"Are Juve and Inter the challengers? Yes, there is interest and the situation is open. We haven't closed the door on anybody yet."