The men, one of whom had a dog, approached the youngster in Bishopbriggs Park and one threatened him with a knife before demanding his mobile.
He then stabbed the teenager in the chest.
The victim was taken to Glasgow Royal Infirmary, but was discharged after treatment for his injuries.
After the attack, which happened about 7.30pm on Monday, both youths ran off towards Kirkintilloch Road.
Police inquiries show the thugs may have been in Tofthill Avenue and Stirling Road following the attack.
Officers are carrying out door-to-door inquiries in those areas.
Police are also asking for help in finding the thugs. Detective Constable Steven Gault said: "This park is popular with local people, some out running and others walking their dogs.
"I am appealing to anyone who may have been in the park around that time to get in touch.
"They may have noticed the men before or after the incident or saw them run off.
"Any information could prove significant and help us trace those responsible."
Both attackers were white. One was about 19, around 5ft 9in, tall and slim. He was wearing a grey hooded top, with the hood up, and a black woollen hat.
The second was about 20 and was wearing a dark tracksuit. He had a dog on a lead.
Anyone with information is asked to call Kirkintilloch police office on 0141 532 4400 or Crimestoppers on 0800 555111.