"I am angry. Physically we were second best and here is the result. I want to win. We have to win. Otherwise, I am going to kill them," the former AS Roma and Juventus coach, who joined last May, told a news conference on Wednesday.
"The teams we face are more compact than we are. They give 100 percent. Since we do not, it is difficult for us."
Ranieri was tasked with leading twice European trophy finalists Monaco back to the French top flight after they were relegated at the end of the 2010-11 season.
They are second in the Ligue 2 standings, one point adrift of leaders Nantes and two points ahead of fourth-placed Guingamp after 17 games. The top three clubs are promoted at the end of the season. (Reporting by Etienne Ballerini; Writing by Gregory Blachier; Editing by Julien Pretot)