"In previous years we have seen support for the group Hezballah, including flags, banners and chanting," the Met's Superintendent Nick Collins wrote to the Campaign Against Antisemitism.
"The MPS is aware of the significant impact that the support for a terrorist organisation can have on the communities of London.
"It fully intends to intervene to enforce the law, where possible, should any offences be disclosed."
Al Quds Day, named after the Arabic word for Jerusalem, is an anti-Israel day of protest held around the time of the final Friday of Ramadan, first initiated by Iran’s Ayatollah Khomeini in 1979.
Hezbollah flags were flown at the London march in June 2018, where one speaker said Israel "should be wiped off the map".
The year before, the march leader Nazim Ali told the crowd "Zionists" were "responsible for the murder of the people in Grenfell".
Stephen Silverman, CAA's director of investigations and enforcement, said: "It was outrageous that Hezbollah supporters were allowed to march through the streets of our capital and we fought long and hard as a community to stop terrorist supporters from being allowed to brazenly flaunt their hatred.
"We are pleased that the police have put in place robust plans to enforce the law.”
