The incident happened between 8pm and 9pm on Saturday, 28 August, at a reservoir area near the Heatherbell railway crossing.
The 17-year-old was subjected to an attack with a knife or sharp instrument and he sustained serious injuries to his back and a facial injury. He was treated at Monklands Hospital and released.
There was a group of people around at the time and officers are keen to speak to two teenagers in particular.
The first one is described as aged 14 to 17-years-old, 5ft 5ins, of skinny build, and had short dark hair with a longer fringe at the front. He was wearing a bright orange top and glasses.
The second is also described as aged 14 to 17-years-old. He was wearing a dark coloured tracksuit with a hood and may have had a black eye.
Detective Constable Nicola Bonnar, of Coatbridge CID, said: “This is believed to have been an unprovoked attack that has left a 17-year-old with serious injuries that required hospital treatment.
“There were a large number of youths in the area at the time and we are keen to speak to anyone who saw what happened or knows the two teenagers described.
“If you can help with our enquiries then please contact us on 101, quoting incident 2189 of Sunday, 29 August, or make a call anonymously to the charity Crimestoppers on 0800 555 111.”