Huntelaar's current deal expires next summer, which has led Heldt to comment that he wants Huntelaar to show his commitment to the club by signing a new deal.
"Huntelaar is to set the agenda," Sky Sports News quotes Heldt as saying. "We want to sign a new deal with him and I feel it would be just reasonable for both parties to sign a new contract.
"However we need him 100% committed. I am unable to force him into signing a new contract at our club.
"We are a Champions League club this season, we were third last season and we are keen to play a big part in this season as well. We are not going to sell our best players."
Huntelaar signed for Schalke in 2010.