The duo stopped at the shop in the southern province's Duc Hoa District and bought a box of beer on Tuesday.
After purchasing the beer, they asked an employee to exchange two dollar bills worth US$100 each into Vietnamese notes.
While the staff was busy counting the Vietnamese notes in a drawer under the table, one of them seized the opportunity, snatched a purse full of cash on the table and fled.
As the two of them ran away to the car parked right outside the shop, other staff rushed after them and successfully took back the purse as well as the box of beer.
Nguyen Quang Vinh, the shop owner, said: "They acted very fast as if they had prepared the theft."
Police are tracking down the two men.
Their nationalities have not been identified yet.