The Metropolitan Police have confirmed eight arrests were made at Tottenham's home Champions League game against Ajax in north London on Tuesday.
Before kick-off, three men were seen breaking up pieces of pavement and wall in the N17 area and throwing them.
Three police officers were assaulted and three men were arrested. A fourth man was also arrested on suspicion of violent disorder and assault on police.
The other arrests happened during the match at Tottenham Hotspur Stadium.
Dutch side Ajax won the semi-final first leg 1-0 thanks to an early Donny van de Beek goal.
Match commander, superintendent Louis Smith said: "Sadly, three officers were injured during the policing operation.
"My officers faced and dealt with serious violence including a group of men who had armed themselves with bricks and bottles.
"Thankfully the officers' injuries are not serious and they remain fit for duty however, this behaviour is totally unacceptable and robust action will be taken against those responsible."