The Metropolitan Police described the incident as "football-related".
A spokesman said a man had been arrested in the area for a public order offence, unconnected to the damage at Piebury Corner.
A man in his 40s was taken to Whittington Hospital in north London with cuts to his head.
A London Ambulance Service spokesman said the man's injuries were not thought to be serious.
More top news
The death toll following the collapse of a six-storey building in Kenya rises to 10 as fears grow for those still trapped in the rubble.
Springwatch presenter Chris Packham describes his battle with depression as "great, hopeless vacuum".
A newly promoted police officer caused a sensation with local women on Facebook