Twelve suspected Extinction Rebellion (XR) organisers have been arrested and several bamboo structures seized ahead of a weekend of planned protests.
Climate change demonstrators and other protest groups are expected to descend on London over the weekend as part of a co-ordinated campaign of "civil disobedience".
Scotland Yard said officers had engaged with the organisers in order to minimise disruption and deter any criminal activity. On Friday morning, they also carried out a series of intelligence-led arrests as part of a "zero tolerance" approach to criminality.
As well as detaining 12 suspects, the force said it had seized items which could be used to cause criminal damage and obstructions, including bamboo structures and lock-on equipment.
Last year, XR protestors blockaded print works in Hertfordshire and Merseyside, interrupting the production of a number of national newspapers. Priti Patel, the Home Secretary, is understood to have told police chiefs she will be very disappointed if demonstrators are able to cause as much disruption again.
Chief Inspector Joe Stokoe, of the Met’s Public Order Command, said: "We know a number of people will be visiting London on Saturday and Sunday in order to protest.
"Our policing plan will be proportionate, with officers engaging with those protesting to ensure their gathering is lawful, safe and doesn’t disrupt those Londoners who are out and enjoying their weekend. We will not tolerate disruptive or unruly behaviour, or any action by groups to intimidate or threaten members of the public, media or police officers.
"We know certain protest groups are specifically intending to disrupt businesses or potentially cause criminal damage to property. This type of behaviour is unacceptable.
"Throughout the week, officers have proactively spoken with businesses, assuring them of our highly visible policing operation and offering crime prevention advice in order to mitigate any risk to their property. Our relationship with these businesses is highly constructive, and I would like to thank them for their support in working with us to deliver this weekend’s policing operation."
He said that on Friday police "took proactive action to prevent and reduce the likelihood of any disruptive activity during the course of the weekend", adding that "this action should further demonstrate our commitment and proactivity to preventing criminality".
The Met said specialist policing teams will "remain on hand during the course of the weekend to respond to any protest activity. Our policing response will continue to be dynamic and officers will act swiftly to any threat".