Mata is a top target for Arsenal and Tottenham.
"I hope that he will stay with Valencia and I think he will do so. We have not received any offers for him so far," Vazquez told regional sports daily SuperDeporte.
"However, we have a back-up plan in case he leaves. That's not just the case for Juan, though. We have a plan like that for every player. We have to be prepared if something happens."
Vazquez claimed Mata was relaxed amid all the speculation.
"Juan is very calm and doesn't get carried away. Of course, the rumours don't go unnoticed, but there is absolutely no doubt about his commitment to Valencia," he said.