The Argentina midfielder joined Villarreal on-loan from Tottenham in January and enjoyed an impressive spell.
Roig Jr told AS: "He is a great player who has been very happy here and we have been very happy with him, but he is a Tottenham player. It is true that we would like him to be able to continue here in whatever capacity next season, but I am already telling you that it is very complicated.
"We have not negotiated with Tottenham, we have not sat down with them to talk about anything for now. We know that the player is open to continue, but we cannot sit down and talk about such an operation without having exits.
"What has been talked about offers and others is not true, there has been no negotiation. Nor have they offered us and asked for anything. As I have told you, it is a very complicated operation, they spent a lot of money on the player and it is not an easy operation. As I have told you, without exits and with the team we have, we are not in a position to carry out this operation."