The former Gent and Twente winger has been linked with a return to Belgium with Anderlecht whilst Dutch giants PSV Eindhoven are also said to be interested.
Ruiz told La Derniere Heure: "If I ever get the chance to play in Belgium or Holland, I would think about it.
"I've good memories of the Belgian league. I still have a lot of friends there."
He added: "I'm looking forward to the world cup. We've a difficult season here at Fulham, but I want to be as fit as possible for the world cup."