Several dozen cabbies drove slowly and tooted their horns at Tower Bridge on Monday, angry that they are banned from the exclusive traffic lanes designated for Olympic athletes and officials.
The so-called "Games Lanes" around greater London are set to come into force Wednesday.
Metropolitan Police say the man jumped into the river but was swiftly pulled out by river police. They say it wasn't clear if the man was a protester. The BBC, however, reported that he was a cab driver.