"We needed a fightback and a fightback is under way," Cameron said in a televised statement after a meeting of the nation's crisis committee. Cameron added that "nothing is off the table" - including water cannon, commonly used in Northern Ireland but never deployed in Britain.
Britain's riots began Saturday when an initially peaceful protest over a fatal police shooting of a 29-year-old father of four in London's Tottenham neighborhood turned violent. It has since morphed into a general lawlessness in London and several other cities that police have struggled to contain.
Police across the country have made almost 1,200 arrests - including more than 800 in London - since the violence broke out.
Thousands of extra police officers fanned out across London, helping the city make it through a night of relative calm, but the chaos and looting moved to other cities.
Vehicles were set on fire in Birmingham, England's second largest city, where a murder investigation was launched after three men were killed in a hit-and-run reportedly as they took to the streets to halt potential rioters.
Armored vehicles and convoys of police vans backed up some 16,000 officers on duty - nearly three times as many who were out Monday night.
Militant online forums are abuzz with calls to Muslims in Britain to launch Internet campaigns in support of the British rioters and to urge them to topple the government.
The Associated Press contributed to this report.