The Netherlands forward was critical of his team's performance in the surprise home defeat after what proved to be Huub Stevens' final game in charge of the Royal Blues
The Royal Blues took the lead through Jefferson Farfan in the 20th minute but soon fell behind as two goals from Jan Rosenthal and another from Jonathan Schmid saw Freiburg claim victory and climb above the hosts to fifth in the Bundesliga table.
Huntelaar himself was controversially sent off after receiving a second yellow for throwing an arm towards an opponent and was clearly unhappy with the way his side performed. Speaking after the game, the 29-year-old Dutch striker was quoted by Telesport as saying:
"We have done far too little. If you create so many chances, you shouldn't lose.
"The cup match next Tuesday against Mainz is very important to us. It will not be easy, but we want to win."
In the wake of this result, which means Schalke have picked up just two points in the last six league games, Huub Stevens was sacked as head coach of the club on Sunday.
Schalke now sit in seventh with 25 points from their 17 fixtures, while Huntelaar has scored five times in the Bundesliga this season.