The FIS council met Saturday in Oberhofen, Switzerland, and "confirmed that one gender is not entitled to participate in races of the other," adding in a statement that "exceptions will not be made to the FIS Rules."
Vonn, a four-time overall World Cup champion, wanted to enter the men's downhill on Nov. 24 at Lake Louise, Alberta, six days before the women race on the same course.
"It's very clear," FIS secretary general Sarah Lewis told The Associated Press in a telephone interview. "It's called the men's World Cup and the ladies' World Cup. The men race the men's World Cup and the ladies race the ladies' World Cup. FIS and World Cup points are not transferrable from one circuit to another."
The FIS statement said Vonn "is welcome to submit a request to the organizing committee and jury to be a forerunner" for the races. Forerunners test the course before races for safety and visibility.
Vonn has earned nine of her 26 World Cup downhill victories in Lake Louise, which is often dubbed "Lake Lindsey" for her dominance there.
Vonn approached the FIS with the request in early October. Following discussions between Vonn, coaches and sport leaders, the U.S. Ski and Snowboard Association (USSA) petitioned the FIS council to consider her request to enter a men's race at some point in her career.
"We're disappointed that the FIS Council did not support the proposal, but also respect its direction," USSA president and CEO Bill Marolt, who is also a member of the FIS council, said in a statement. "Lindsey Vonn is a great champion in our sport and we have always respected her interests in this new challenge."
Alpine Canada president Max Gartner was disappointed about the decision.
"I saw it as a great opportunity to raise the profile of the sport by attracting interest from people who do not normally follow ski racing, particularly in North America," Gartner said in a statement. "It would have provided a great platform to showcase our sport and the amazing athletic performances of our athletes."
Lewis said while there was no vote, the 17-member council was in general agreement over the decision.
"This decision had nothing to do with an individual. It's not personal, it's not specific to Lindsey and it's not underlying her skills," Lewis said, adding that the USSA handled Vonn's request "eloquently."
Still, Gartner wasn't satisfied.
"Lindsey has achieved many milestones in ladies' ski racing," he said. "It would have been interesting to see how she stacked up against the best male racers in the world. Lake Louise is the perfect venue to have that comparison because Lindsey has as much experience on the mountain as many of the men have had."
Vonn has said she wants to race the grueling Streif course in Kitzbuehel, Austria, after she retires.
"I hope Lindsey gets a chance to fulfill her dream at a later date," Gartner said.