Two people have been arrested at a pro-Palestinian protest in Brixton, south London.
People sat in the road blocking the path of the police cars carrying the arrested protesters, the Metropolitan Police said.
One man was arrested because of the placard he was carrying - police said he was detained "on suspicion of a racially aggravated public order offence".
Police did not release details of what the placard said.
Met Police said on X, formerly Twitter: "When officers tried to leave the area their vehicle was surrounded by other protesters. Some sat in the road blocking their path.
"Additional officers were deployed and the arrested man is now on his way to custody."
A male teenager was arrested on suspicion of criminal damage of a police vehicle.
People again tried to block the police van as it drove off and were moved out of the way by officers, police said.
Last weekend police handed out leaflets to pro-Palestinian protesters warning them about potential criminal offences.
The leaflet warns against using "words or images that are racist or incite hatred against any faith", that "support Hamas or any other banned organisation" or "that celebrate or promote acts of terrorism - such as the killing or kidnap of innocent people".
"If in any doubt bin any placard or sign that might break these rules," it says.
The leaflet also tells those attending to check if any restrictions are in place and warns: "Don't cause fear or be violent, including using flares or fireworks, or using threatening words or aggressive behaviours that could be considered intimidating.
"Don't deface or damage statues, monuments or other property."