The Swiss international, who started just two times for the German club last season, has said that he would look to discuss his future if he does not get first-team assurances.
"I am under contract with Schalke until 2015," he told BILD.
"I have not been playing that regularly and, if I feel I will not have a greater chance of regular first-team appearances, I will have to discuss my future with the club. This is a fact."
Barnetta joined the club on a free transfer from Bayer Leverkusen last summer.