The playmaker scored in the Euro 2012 final in the summer and has been in impressive form for the Blues so far this season.
However, the former Valencia man has been snubbed by Vicente del Bosque, and admits that he thought that he was going to be included.
"I was excited about these games and confident I would make the squad," Mata told The Sun.
"I've not spoken to the manager. The only thing I can do is keep playing well in order for him to pick me."
La Roja face Belarus and France in their World Cup qualifiers.