The unidentified man entered the store in the city's Mitte district on Tuesday, placed a rucksack on the counter, produced a knife and started gesticulating wildly at the two female staff members, police said.
The would-be robber then vaulted over the counter and continued a series of hand gestures that only further confused the women, 'The Local' reported.
One of the women ran into the street calling for help, prompting the man to flee after abandoning both knife and backpack.
It was only later that the staff realised the robber wanted them to fill the backpack with cash from the register, the report said.
Police were searching for the man after the incident.
