Plastic bullets have been considered by police chiefs as a tactic to bring the unprecedented rioting under control.
Deputy Assistant Commissioner Stephen Kavanagh said Scotland Yard was "not going to throw 180 years of policing with the community away" as the prospect of using the ammunition for the first time at a British disturbance was raised.
"The use of any tactics will be considered carefully," he said. "That does not mean we are scared of using any tactic."
Officers said they hoped they were wrong as they said they were "preparing for mass disorder again" tonight.
Senior Scotland Yard officers, led by Acting Commissioner Tim Godwin, met a number of departments last night to discuss the use of various tactics.
Asked about other tactics, such as plastic bullets or baton rounds, Mr Kavanagh said: "Through the night the Commissioner did absolutely consider that as one of the tactics available to use, a tactic used if deemed necessary.
"These are very fast-moving mobs - by the time we get baton guns there, they will have moved on."
Mr Kavanagh said armoured vehicles, known as "Jankels", had been used for the first time last night.
"The use of armoured vehicles driving at speed towards these looting individuals is a new tactic never used before.
"It's quite shocking for the people of London to see that's what we have to do."
Soldiers in Northern Ireland have used plastic baton rounds in the past.
In 1975 Stephen Geddis, 10, became the first person to die after being hit by a plastic bullet in Belfast.
Mr Kavanagh said baton rounds have been available to police for the last three nights.
"Rest assured we are not going to throw 180 years of policing with communities away lightly," he said. "If that is a tactic that is used it's going to be properly considered and the repercussions for it and the change in the way that we police will be long lasting but that does not mean the police is scared of using any tactic."