The 17-year-old striker is highly rated by the Italian manager and scored in the 2-0 win over Rennes on Saturday in what was a rare start for the Frenchman.
"[Anthony Martial] is a good player and scorer of goals," Ranieri told reporters. "He worked well for the team. I have the experience to know when it is a good time to give a player a debut.
"He is more attentive and focused at the moment. He is tough, young and has the right mentality. I'd prefer him to stay at Monaco in the January transfer window. With so many champions around him, he can learn a lot.
"He has the quality to become a great player, the potential to have a great player. But the most important thing is to be professional."
Monaco, who sit third in Ligue 1, travel to face Nice on Tuesday night.