Young athletes could be exploited if the Enhanced Games are allowed to go ahead, International Federation of Sports Medicine (FIMS) President Fabio Pigozzi said.
The Enhanced Games would allow athletes to use pharmacological or technological assistance, including substances banned by the World Anti-Doping Agency (Wada).
The concept has been met with widespread criticism, with the International Olympic Committee (IOC), Wada and World Athletics having denounced the proposed competition.
Enhanced Games President Aron D'Souza has said, however, the competition would conduct rigorous health testing.
FIMS said it welcomes the decision by Enhanced Games to conduct medical screening, but warned that current technology could not ensure the safety of athletes or mitigate the health hazards of many banned substances.
In a statement published on Friday in the British Journal of Sports Medicine, Pigozzi said FIMS's priority was to safeguard "scientific analysis, study of the physical condition of the individual, and protection of health."
"These principles are incongruent with the current philosophy and mission of the Enhanced Games," Pigozzi said.
"The grave concern of FIMS is that young individuals will be exploited in the quest for fame and fortune and the allure of the Enhanced Games."
Enhanced Games did not immediately respond to an emailed request for comment.