A special team set up to target criminals and potential troublemakers ahead of the Notting Hill Carnival has arrested eight people.
Last year 18 people were arrested in a similar operation
Letters warning people to stay away from the west London street party will be sent out to anyone who has been involved in trouble at past carnivals.
Commander Chris Allison said it was vital a small minority does not spoil this "vibrant and unique event".
Police will seek to ban those arrested from carnival under bail conditions.
Over carnival weekend officers will use CCTV to spot, track and arrest those breaking bail conditions.
Police said they have arrested people for a variety of offences since the operation began in June.
Last year a similar operation resulted in 18 arrests and half a kilo of cocaine, two guns and ammunition, 27 stolen mobile phones, £13,000 worth of counterfeit currency and numerous stolen credit cards were seized.
Commander Allison, said: "With so many people gathered in one area the carnival can provide a target-rich environment for criminals.
"Last year serious offences were down and we want to keep them down in 2005.
"Our message is clear - if you are coming to this year's carnival intent on committing crime then it is more than likely we're already aware of you, and if we have the grounds we will arrest you."