The Metropolitan Police confirmed all of the arrests made during the demonstration at Trafalgar Square are for showing support for a proscribed organisation.
The group was banned for breaking into a UK air base and spray painting two military planes in 2025. The protesters also targeted arms manufacturers in Britain that were selling Israel weapons amid the war in Gaza.
The ages of those arrested range from 27-years-old to 82-years-old, the force said.
In a post on X, the Metropolitan Police added that its officers are "continuing to make more arrests and a group remains in Trafalgar Square".
Hundreds of protesters gathered in Trafalgar Square on Saturday afternoon with signs reading "I oppose genocide. I support Palestine Action".
Many of the mostly elderly demonstrators sat on camping chairs and on the ground as they held up their placards.
At the top of the square, near the National Gallery, large banners were displayed reading "Israel starves kids".
Several individuals, including a man and a woman with grey hair, were carried off by officers away from the demonstration.
Police officers could be seen carrying a lady from the protest as people chanted "shame on you".
Police then lifted a man out in handcuffs and walked an elderly protester with a walking stick to the police vans.
One woman shouted: "Yeah she looks like a terrorist, doesn't she mate?"
Protesters, some of whom were carried by their ankles and under their arms by officers, were led to an area at the side of Trafalgar Square surrounded by a metal fence.
In March, the force said officers would resume arresting suspected Palestine Action supporters, as a High Court battle over the ban on the group continues.
The police paused the arrest of demonstrators in February after the High Court ruled the UK government's ban was unlawful, but then decided to resume as an appeal against the ruling is likely to take several months.