The gang, made up mainly of Romanian nationals, had been posing as officers in some of the top tourist spots in Geneva and neighbouring Vaud, police said on Friday.
The set-up was always the same: a plain-clothed member of the gang would ask an unsuspecting tourist for directions, only to be interrupted by two accomplices wearing police uniforms demanding to see his and the tourist's identification.
With the tourist's wallet in hand, the phony officers discretely pocketed the cash inside.
Police said they had arrested seven members of the gang, which worked in two teams believed to be behind some 30 such cases in Geneva and five in Vaud in the past six weeks.
Victims said the gang had made off with nearly $35,000 (€26,000) in cash.