Two people have been arrested on suspicion of arson after a memorial wall in Golders Green, north London, was damaged on 27 April.
The Metropolitan Police said a 46-year-old man and a 38-year-old woman were arrested on Monday morning as part of a counter-terror policing investigation.
The two suspects, who were arrested in Romford, remain in custody at a London police station.
Cdr Helen Flanagan said police are "committed to protecting vulnerable communities in the capital".
The wall in Golders Green was used as a space to display photos of protesters killed by the Iranian government during a crackdown on demonstrations in January.
A section also commemorates those killed in the 2023 Hamas attack on the Nova music festival in Israel, with a more recent message of solidarity with the Jewish community attached to a nearby tree.
The wall itself was not damaged, though a nearby cabinet was burned.
The Met said it was continuing its investigation into the incident and officers were searching an address in Romford.
Flanagan said: "[Counter Terrorism Policing] London is working on a number of investigations into incidents that have taken place in north west London since the attack on Hatzola ambulances in Golders Green in March.
"We have made a total of 30 arrests and nine people have been charged.
"Counter-terrorism officers continue to work closely with our colleagues in the Metropolitan Police in response to the various incidents.
"We're providing protective security advice and support to various organisations, community venues and businesses."
On Thursday, the UK's terrorism threat level was lifted from "substantial" to "severe" for the first time in more than four years.
That decision came shortly after two Jewish men were stabbed in Golders Green on Wednesday.
Essa Suleiman, 45, has been charged with three attempted murders.
He is also accused of attacking Ishmail Hussein, a man he had known for around 20 years, in Southwark, in London, on Wednesday.
Security minister Dan Jarvis said it was "not solely as a result" of the Golders Green attack, but also "an increase in broader Islamist and extreme right-wing" threats.
Update: An earlier version of this article included a Metropolitan Police statement which said the two suspects had been arrested on suspicion of arson with intent to endanger life. The Met later said its original statement was incorrect and the suspects had been arrested on suspicion of arson. This article has been updated to reflect the latest statement.
