Hundreds of anti-gentrification protesters took to the streets of Shoreditch to protest against unaffordable housing and the perceived social cleaning of London.
During the protest the word "scum" was written on controversial cafe Cereal Killer Cafe where a bowl of cereal costs about £4.
Cafe owners said they, and their customers, were terrified when protesters wearing pig masks and carrying flaming torches attacked the shop in Brick Lane.
Alan Keery, 33, said: "They see us as one of the biggest symbols of gentrification in the area."
The cafe boss, from Belfast, who runs the establishment with his twin brother Gary, said it was "absurd" that activists were targeting their shop, which they said was just a small business.
"It's bullying at its best," he said.
Police say "missiles" were thrown and a "criminal element" in the group caused damage to shops and businesses around Brick Lane.
An estate agent's window was also smashed and a police officer was injured after a bottle hit him in the face.
One person has been arrested on suspicion of criminal damage.
The Cereal Killer Cafe is the UK's first speciality cereal cafe selling more than 120 types of cereal from around the world.