Anyone attempting to disrupt the royal wedding on Friday will face a "robust" response, the Metropolitan Police has said.
Some 5,000 officers will be on duty to ensure the marriage of Prince William and Kate Middleton is a "safe, secure and happy event".
Cdr Christine Jones, who will be overseeing the police operation, said there was no specific known threat.
But 60 suspected troublemakers have been banned from London on the day.
They are people who were arrested following the recent student protests and the violence during the TUC marches. They have been banned from central London as part of their bail conditions.
Six have been arrested in recent days amid fears they could be planning similar disruption and police are expected to make several more arrests in coming days.
Meanwhile, the first member of the public has begun camping out in front of Westminster Abbey.
John Loughrey, 56, began his week-long vigil on Monday night, saying he planned to stay in his position to ensure a prime spot for the event.
The world's media has also started arrive at a temporary structure outside Westminster Abbey where they will be broadcasting to an estimated global TV audience of two billion.
'Eyes and ears'
Cdr Jones said intelligence suggested there was currently no specific threat to the "meticulously planned" event.
"We would be wrong not to consider spontaneous protest as part of our contingency planning. But let us make it absolutely clear - this is a day of celebration, joy and pageantry. It is a fantastic day for Britain," she said.
"Any criminals attempting to disrupt it, be that in the guise of protest or otherwise, will be met by a robust, decisive, flexible and proportionate policing response."
Scotland Yard is continuing to negotiate with radical Islamist group Muslims against Crusades over proposed protests, after its application for an event at Westminster Abbey was rejected.
Nationalist group the English Defence League had threatened to hold a counter-demonstration if the police granted permission to Muslims against Crusades. It has since said that no counter-protest will be held.
Elsewhere, a separate protest group with Middle Eastern links has warned police it is planning disruptions, after a man walked into a London police station over the weekend to formally apply for permission to demonstrate.
Police have powers to ban any major protests along the main route that the royal couple will take but are unable to rule out "static" protests taking place at other nearby locations.
Police called on the thousands of people planning to attend to help them on the day, by being their "eyes and our ears".
Assistant Commissioner Lynne Owens said at a news conference: "If you see anybody in the crowd that is acting suspiciously please bring it to the earliest attention of our officers.
"There will be thousands of officers on duty, lining the route, and they are there to help you."
As well as the Royal Family, 50 heads of state are attending the ceremony, which it is anticipated will be watched by up to two billion people on television. There will be 70-80 close protection teams for VIPs on the day.
Ken Wharfe, former royal protection officer to Diana, Princess of Wales and Princes William and Harry, said the police were well prepared.
"The great thing about Scotland Yard is it has this fantastic expertise in dealing with ceremonial events - as distinct from demonstrations we've seen recently.
"So given all that expertise and given almost this bottomless pot of cash that David Cameron said 'look have this', there won't be a problem."