Mata, a member of Spain's World Cup winning squad last summer, is said to be a target of several Premier League sides, including Arsenal, Liverpool and Tottenham Hotspur.
Earlier this month, Valencia President Manuel Llorente had been insistent that the player was not for sale. However, comments made this week by manager Unai Emery suggested a move was still a possibility.
"We want him to stay and Mata has also expressed his wish to remain at Valencia, but we know that if a big-money offer comes in from a club and it's good for both the player and the club, it could lead to his exit," Emery told Cadena Copa.
And the 23-year-old has now once again confirmed his happiness to remain at the Mestalla for the coming season, and appeared to suggest that whether or not he moved on would be up to his club.
"I have never said I want to leave," Mata said, according to reports in Spanish newspaper Marca.
"From here to August 31, if there are any offers then the first to know about it will be the club. I never said I wasn't happy here.
"There's no point speaking about suppositions. I like to talk about realities. I am very relaxed because if there is anything, the club will assess it.
"I know the boss said something yesterday [regarding a possible transfer], but I am not aware of any offer having arrived."
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