The prime minister has described a planned march on Armistice Day as “provocative and disrespectful”.
Tens of thousands of demonstrators will take to the streets on 11 November.
The Met Police has vowed to use all its powers to stop the disruption of commemorations.
The prime minister has been accused of “encouraging far-right activists” with comments he made about pro-Palestinian protests.
Rishi Sunak described a planned march on Armistice Day as “provocative and disrespectful” and claimed there was a “clear and present risk that the Cenotaph and other war memorials could be desecrated”.
Tens of thousands of demonstrators are planning to take to the streets to call for an immediate ceasefire in Israel’s attacks on Gaza on Saturday 11 November.
The Palestine Solidarity Campaign (PSC), which is organising the march in central London, has criticised Sunak’s comments and suggested he could be “encouraging the calls from far-rights activists and commentators who appear to be inciting action on the streets.”
There are fears the march could disrupt the two-minute silence commemorating the war dead and the daytime and evening Festival of Remembrance at the Royal Albert Hall, with the latter performance usually attended by royals.
Sunak and home secretary Suella Braverman have claimed there is a possible risk of disorder.
But the PSC has already confirmed it has “no intention of marching on or near Whitehall” and added the protest would begin nearly two hours after the annual two minute silence at 11am.
The PSC said in a statement: “Given these facts, we are alarmed by members of the government, including the prime minster, issuing statements suggesting that the march is a direct threat to the Cenotaph and designed to disrupt the Remembrance Day commemorations.
It added: “Such statements are encouraging the calls from far-rights activists and commentators who appear to be inciting action on the streets to stop the protests taking place and are deeply irresponsible.
“Given the wider context of the previous statements by the home secretary seeking to demonise all of those marching in support of the rights of the Palestinian people, it is clear that these further statements are motivated by a desire to suppress widespread public support for an end to Israel’s bombardment of the people of Gaza.”
The Met Police has vowed to use all its powers to stop the disruption of commemorations and said officers will be deployed across the capital that weekend as part of a “significant policing and security operation”.
Watch: Pro-Palestine protests on Remembrance Day ‘not acceptable’ says security minister
‘Provocative and disrespectful’
Writing on X, formerly Twitter, Sunak said: “To plan protests on Armistice Day is provocative and disrespectful, and there is a clear and present risk that the Cenotaph and other war memorials could be desecrated, something that would be an affront to the British public and the values we stand for.
“The right to remember, in peace and dignity, those who have paid the ultimate sacrifice for those freedoms must be protected.
“I have asked the home secretary (Suella Braverman) to support the Met Police in doing everything necessary to protect the sanctity of Armistice Day and Remembrance Sunday.”
Braverman and the immigration minister, Robert Jenrick, backed the prime minister’s assessment, with the home secretary branding such a demonstration a “hate march”.
She tweeted: “I agree with the Prime Minister. It is entirely unacceptable to desecrate Armistice Day with a hate march through London.”
Jenrick wrote: “Armistice Day is sacrosanct. These disrespectful and often hate-filled marches, routinely intimidating our fellow citizens, must not be permitted to demean our national moments of remembrance.”
'We will take a robust approach'
The Met Police said protest groups have not indicated plans to march on Remembrance Sunday on 12 November but a significant demonstration is expected on the Saturday.
Met Commissioner Sir Mark Rowley, in a letter to Sunak, said: “Like you, I recognise the profound significance of Armistice Day and the events that take place across the weekend in central London and in communities across London.
“We will take a robust approach and yesterday I set out our intent to use all the powers available to the MPS, including putting in place conditions, if required, to ensure events in Whitehall and the surrounding areas as well as other locations of significance across London are not undermined.”
London mayor Sadiq Khan said it is “incredibly important” that demonstrators understand the importance of Remembrance events and the Met Police was speaking to protest organisers to “make sure they stay away from the Cenotaph”.
He added: “I’d encourage the organisers to work with the police to stay away from the Cenotaph.”