Officers were called to the scene in North London after a stabbing late last night.
An 18-year-old man was arrested on suspicion of being in possession of an offensive weapon and affray, following the incident on Chatsworth Road.
The victim, also 18, was described by Scotland Yard as having “serious but not life-threatening injuries” after being found with stab wounds to his torso.
As officers arrived on the scene, they were greeted by a crowd of 30 people who had their faces covered.
The group, proceed to launch bottles and other missiles at them.
No officers were injured during the trouble, “despite continuing threats from a volatile crowd”, a Metropolitan Police spokesperson said.
In a statement, Scotland Yard added: “Officers at the scene were threatened by a large group of around 30 people. The group had covered their faces and threw bottles and other missiles at police. No officers were injured during this incident.
“One emergency response team officer pursued and apprehended a suspect in connection with this incident despite continuing threats from a volatile crowd.”
Detectives in Hackney are appealing for witnesses to speak to them.