The Portugal international has shone since his arrival on-loan from PSG.
Marcelino told Radio Marca: "Did I talk with Peter Lim to make an effort to keep Guedes? We are talking about the majority, if not all players in the squad.
"From a sporting and human point of view, he fits perfectly with our idea of a game. He has quality and a great future in front of him.
"The technical staff would be happy to have Guedes this season and next. But Valencia must decide."