He was reported to have come close to joining Real Madrid over the summer, and Los Blancos remain keen, while Barcelona, Manchester United, Chelsea and Manchester City are also believed to hold an interest.
"The exit of Villa will be dependant on us identifying a suitable replacement," Emery said. "At the moment the club is working on that, but any decision will not rest with me.
"My mission is to prepare the squad for the present and not think too much about the future.
"Valencia will always be a big club and we do not depend on just one or two players."