A march can only be banned if police consider it would result in serious public disorder, and that placing restrictions on it would not prevent that disorder from taking place. The decision needs approval from the home secretary.
Harman said he did not believe the strict legal threshold required in order to request such a ban had been met.
Neither the police or the home secretary can ban static demonstrations, although conditions can be placed on them.
Harman said that if the march went ahead, police would use their “full powers” to ensure there were “appropriate conditions” in place, including on the route and timing of the march.
Police say anyone who breaches conditions will be arrested and officers will take a zero-tolerance approach to hate crime.
Harman said although officers had made “every effort through formal and informal channels” to identify the organisers behind the event, they had been unable to do so.
“If it goes ahead, we will have to police it,” he added.
Around 1,200 people were killed by Hamas fighters in the attacks on Israel on 7 October 2023, and 251 people were taken hostage.
This triggered a massive Israeli military offensive in Gaza, which has killed over 70,000 Palestinians.
In June, a UN commission of inquiry concluded that Israel is committing genocide, and a resolution passed by the International Association of Genocide Scholars (IAGS) in September came to the same conclusion.
More than 900 people have been killed in Israeli attacks in Gaza this year despite the ceasefire, according to latest figures from the territory’s Hamas-run Ministry of Health.