Matt Twist, assistant commissioner, told the Home Affairs Select Committee that police had intel about disruption.
The force has been criticised for arresting six members of anti-monarchy group Republic and three women's safety volunteers.
Republic said it had "no intention" of causing disruption by protesting.
Mr Twist told MPs that the force had received intelligence there was going to be a "concerted attempt to disrupt the Coronation procession" on 6 May.
He added they had been so concerned they alerted Home Secretary Suella Braverman and London Mayor Sadiq Khan the night before the celebrations began.
Police were given extra powers shortly before the Coronation under a controversial new law, the Public Order Act 2023.
This resulted in protesters, including the chief executive of Republic, Graham Smith, being held in police custody for almost 16 hours, then bailed. They were later told that no further action would be taken against them.
The three women's safety volunteers who were arrested were also released without charge. Westminster City Council has said it asked for an apology from the police to the Night Star volunteers, who hand out rape alarms.
Mr Twist was asked by committee chairwoman Diana Johnson whether he felt any political pressure to make arrests during the Coronation.
He responded he only "felt pressure to deliver a safe and secure operation, but that was because of the fact that it was a once-in-a-lifetime event for so many people".
He added it was the biggest protection operation the Met has run, with 312 protected people that they had to get in and out of the Abbey in about 90 minutes.
"So the stakes were enormously high, so I absolutely felt pressure to deliver a safe and secure operation. But that wasn't political pressure," Mr Twist said.
The hearing was briefly interrupted by Just Stop Oil activists who were sat behind Mr Twist wearing white t-shirts with the name of their group written in large letters.
Voices could be heard in the chamber along with people groaning and asking for security to intervene, while eight Just Stop Oil members were also arrested in Parliament Square.
When the hearing resumed following the brief interruption, Mr Twist told the committee that police believed the threat to the Coronation was real.
He added they had had short notice between the act getting Royal Assent and the police being informed. However, he believed officers knew what they had to do on the day.
Anti-monarchy protester Matt Turnbull told the committee police officers were interested in some luggage straps that Republic were using to hold their placards together.
Mr Smith added his group had brought 600 placards in their van, which explains why they needed trolleys and the straps.
Mr Twist said arrests were made after officers found 12 heavy duty straps with combination locks in sealed plastic bags.
Tim Loughton, Conservative MP for East Worthing and Shoreham, asked Mr Twist if he had seen luggage straps with combination locks used to lock on protest signs.
He said he hadn't, but that didn't mean it didn't happen.
Suzie Melvin, who volunteers for the Night Stars safety scheme and was arrested during the Coronation weekend, also spoke to MPs.
She described how the team were wearing hi-vis jackets "with the Metropolitan Police logo" due to their partnership with the force,and backpacks in the early hours of the Saturday morning on the Coronation weekend.
As they approached Soho Square in central London, officers looked through their bags and they were arrested and taken into police custody, despite them showing emails and leaflets from Westminster City Council and the Night Stars website, she said.
Ms Melvin stated the arresting police officer told her they were "specifically looking" for people from her organisation. She believed it could have been linked to volunteers carrying rape alarms, part of an "anti-spiking kit" they hand out to people enjoying a night out.
The Met previously said it had "received intelligence" people "were planning to use rape alarms to disrupt the procession".
Ms Melvin was released the day after the Coronation.
This led committee chairwoman Dame Diana Johnson to reply: "I am speechless."
Meanwhile, a complaint has also been lodged by royal fanAlice Chambers, 36, who was held in custody for 13 hoursafter she was mistaken for a Just Stop Oil protester while waiting in the Mall to see the King.The Metropolitan Police have said it regrets she was not able to watch the Coronation. She was released with no further action.
A total of 64 arrests were made during the policing operation for the Coronation, the Met said.
The police said 52 of those were related to concerns people were going to disrupt the event.