Police drew their batons during clashes, and one protester was seen with blood streaming down his face behind a barrier after being arrested.
Hundreds of people were risking arrest at the protest as they showed support for Palestine Action, which has been banned by the Government as a terrorist organisation.
Piers Corbyn, the brother of former Labour leader Jeremy Corbyn, was among those arrested.
He was seen encouraging protesters from the back of a police van as it was driven out of Parliament Square.
Scotland Yard said its officers experienced physical and verbal abuse as they arrested people for backing the group.
The force said: “Officers continue to make arrests of individuals showing support for the proscribed terrorist organisation Palestine Action at the Defend Our Juries protest.
“There has been a co-ordinated effort to prevent officers carrying out their duties, which has included physical and verbal abuse.
“A number of arrests have now been made for assault.”
READ MORE: What it was like as Police Scotland let a Palestine Action protest go ahead silently
The Met confirmed around 150 people have been arrested so far.
There were frantic scenes in the area throughout the afternoon, as officers forced their way through crowds carrying arrested protesters, had screaming arguments with demonstrators and had water and plastic bottles thrown at them – while several protesters fell over in a crush at one point.
Despite the violence, which occurred particularly on neighbouring streets, Parliament Square Green remained largely peaceful.
Several hundred protesters, many of them elderly, spent the day on the grass, with signs reading “I support Palestine Action”.
Elsewhere in the square, dozens of doctors in their scrubs – with badges pinned to them identifying their roles including: doctor, surgeon and physio – unfurled a banner reading: “Medical duty & terror law”, while families of Holocaust survivors held a sign which said: “Holocaust survivor descendants against genocide”.
Kerry Moscogiuri, of human rights campaign group Amnesty International UK, said: “When the Government is arresting people under terrorism laws for sitting peacefully in protest, something is going very wrong here in the UK.
“Criminalising speech in this context is only permitted when it incites violence or advocates hatred. Expressing support for Palestine Action does not, in itself, meet this threshold.”
A spokesperson for Defend Our Juries (DOJ) said: “State repression has not worked.
“This is becoming Labour’s Poll Tax moment. The resistance to this ridiculous ban keeps on growing exponentially. It is also bringing together social movements in common cause.”
