The coronation will be one of the most important security operations ever conducted in Britain, Home Office minister Tom Tugendhat said.
The Minister of State for Security was speaking hours after the arrest of a man who threw suspected shotgun cartridges into the grounds of Buckingham Palace.
He is being held on suspicion of possessing an offensive weapon after a knife was found in his possession during the incident on Tuesday night, the Metropolitan Police said.
"We're in no way complacent" Mr Tugendhat told Sky News on Wednesday. "I'm very glad to see that the police reacted incredibly quickly, incredibly professionally, to the incident last night."
Mr Tugendhat told Radio 4's Today show he was "very encouraged" by the response of the police.
"I thought they behaved entirely appropriately and very, very quickly responding to last night's incident," he said adding the coronation is a "major moment for the United Kingdom".
The force is preparing for hundreds of thousands of people to descend on the capital on Saturday for the coronation of King Charles III at Westminster Abbey to mark his accession to the throne.
In the centre of London large parts of Victoria, Mayfair, Whitehall and St James's Park surrounding the 2km coronation route have already been closed ahead of the event.
“What we’ve been planning for a number of months now is one of the most important security operations that the country has put into plan,” Mr Tugendhat told Times Radio.
“The reason for that is this coronation is not just an opportunity to celebrate our new King, but also an opportunity to showcase the United Kingdom to the world.
“So we’re very conscious that there are going to be quite literally thousands, possibly hundreds of thousands of foreign tourists, there are going to be many film crews and journalists from around the world and of course, we’re going to have heads of state and government coming to celebrate with us on Saturday.
“So this is an enormously important moment for the country. The police are, to put it mildly all over it and our intelligence and other security forces are extremely aware of the challenges that we face and ready to deal with them – as the police did quite brilliantly yesterday.”
