The incident occurred at the end of the fireworks display, attended by the Geneva member of parliament and his wife, which ended the festival at the weekend.
According to news reports initially revealed by the 20 Minutes newspaper, Stauffer, 47, was rebuffed when he attempted to leave the VIP stand by an exit reserved for security personnel.
Stauffer, chairman of the populist Mouvement citoyens genevois (MCG) party, “went crazy and became aggressive” after being told he could not leave by that exit, Le Matin reported on Wednesday.
After being sprayed in the face he ran to the lake for water to relieve the effects of the gas before police arrived at the scene.
Stauffer later phoned Monica Bonfanti, the chief of Geneva police, to protest the actions of the security official.
On Monday, he lodged an official complaint with justice authorities, alleging an assault.
The incident is just the latest in a string of high-profile altercations involving the MP.
In 2008, he was ejected from parliament after being accused of insulting other politicians.
In February 2011 he engaged in a shoving match with a Green Party MP at the city hall bar.
In February this year, he threw water in the face of another MP while parliament was sitting.
Stauffer maintained that he can control his emotions.
“On Saturday night I was only defending myself because the security official lost his self-control and was spraying everybody,” he told Le Matin.
“This behaviour is unacceptable.”
The case is now in the hands of Geneva’s chief prosecutor.