Prime Minister David Cameron has tweeted:
I'm appalled by the murder of a Palestinian teenager. The loss of four boys this week is a terrible reminder of the need for lasting peace.
More top news
A humid night for some with thundery downpours in places.
The 20-year-old was found fatally wounded on Roth Walk, near Finsbury Park, north London at around 3am on Saturday, Scotland Yard said.
Daniel Cowell has been jailed for five years and four months after ramming a police patrol car with a stolen transit van.