A massive police operation is being planned for the event.
The Government has blocked 11 foreign “far-right agitators” from entering the UK for a Tommy Robinson-led demonstration on Saturday.
Prime Minister Sir Keir Starmer said the Unite the Kingdom rally’s organisers are “peddling hatred and division”.
More than 100,000 people could attend the central London event, with police planning an operation on a scale “unprecedented in recent years”.
The Home Secretary has the power to cancel a person’s permission to enter or stay in the UK, and Sir Keir signalled a tougher stance on those he described as “far-right agitators” during a speech earlier this week.
Right-wing personalities claiming to have been barred include Polish politician Dominik Tarczynski, Belgian politician and commentator Filip Dewinter, anti-Islam influencer Valentina Gomez, US commentator Joey Mannarino, Spanish personality Ada Lluch, Dutch anti-immigration activist Eva Vlaardingerbroek and US-based podcaster Don Keith.
As he visited a Metropolitan Police operation room on Friday, the Prime Minister said: “We’re in a fight for the soul of this country, and the Unite the Kingdom march this weekend is a stark reminder of exactly what we are up against. Its organisers are peddling hatred and division, plain and simple.
“We will block those coming into the UK who seek to incite hatred and violence. For anyone who sets out to wreak havoc on our streets, to intimidate or threaten anyone, you can expect to face the full force of the law.
“My Government will always champion peaceful protest but will act decisively against hatred. We all have a responsibility to speak out against those spouting vile divisive views wherever we see it.
“We are a country built on decency, fairness and respect, at our best when people from different backgrounds come together in common purpose. That is what we must fight for.”
Saturday’s rally has been organised by Robinson, real name is Stephen Yaxley-Lennon.
The previous Unite the Kingdom protest in September was attended by between 110,000 and 150,000 people.
A massive operation is being planned by the Met as two protest marches and the FA Cup final take place.
Thousands of officers will take to the streets and armoured vehicles will be deployed along with police horses, dogs, drones and helicopters as the Met aims to avoid clashes.
Heavy restrictions have been put in place in a bid to keep the Unite the Kingdom and pro-Palestine Nakba Day rallies separate, with added concerns that some football fans will go straight from the FA Cup final to the Tommy Robinson event.
Live facial recognition will also be used for the first time at a protest.
