The incident happened around 6.15am this morning when a man wearing a motorbike helmet entered the store with a weapon.
He stole money and fled the scene on a black moped.
Two female staff members witnessed the attack. They were not injured but were left upset.
The suspect is white and wore a red and sliver helmet, a black North Face jacket with grey sleeves, grey trousers and white trainers. He was also carrying a black Adidas rucksack.
Ladies Day at Musselburgh Races: Children's nurse crowned most stylish woman
Edinburgh dad Joseph Wakeley dies days after being hit by car near Sheriffhall Roundabout
Livingston crash: 28-year-old woman pronounced dead at scene as man arrested in connection with incident
Pedestrian dies after being hit by car in Edinburgh
Edinburgh crime: councillor Kevin Lang left shaken after being ‘grabbed by throat’ while delivering newsletters
Police said extra patrols will be carried out in the area to reassure locals.
Detective Inspector Paul Grainger said: “This was a frightening attack which has left the two female members of staff badly upset.
“We are eager to trace the man responsible as soon as possible.
“I would ask anyone who was in the Lindsay Road area on the morning on Sunday May 28 to get in touch with us immediately.”