Police closed a section of Kingsland Road in both directions after receiving reports of a man standing on a nearby roof.
Officers closed part of the Hoxton end of the road, and there were long queues of traffic in the area, with motorists being advised to use alternative routes.
Passers-by hit out at crowds of people who gathered close to the cordon to watch the incident unfold, some of whom took pictures of the man on the roof.
Stephanie Jayne Hope tweeted: "Human beings are disgusting. A man threatening to jump off a building and we're all stuck on Kingsland Road and people are taking photos."
London Fire Brigade, London Ambulance Service, and the Metropolitan Police were called to the scene.
A police spokeswoman said: "We were called at 10.22am to report of a man on a roof.
"Local road closures are in place, motorists are advised to avoid the area."
The man came down from the roof at around 1pm, and was taken to hospital for treatment under the Mental Health Act.
