An Australian teenager has been seriously injured in an unprovoked stabbing attack at a McDonalds in New York City on Monday.

Police were called to the fast-food outlet on Eight Avenue about 2am after a 19-year-old was stabbed while eating inside the restaurant, according to sources cited by New York Post.

Officers arrived at the scene, just a short walk from Times Square, to find he had suffered stab wounds to his ribs and back. Paramedics raced the young Australian to Bellevue Hospital in a stable condition.

While at the scene police arrested 25-year-old Juan Mercedes and charged him with second degree assault.

Investigators are still piecing together the circumstances surrounding the incident, but early reports suggest the pair were talking to each other before an unprovoked Mr Mercedes allegedly stabbed the teen.

The tourist has not yet been identified and Mr Mercedes remains in custody as he waits for an arraignment.