Britain is in "the last-chance saloon" to solve the social problems behind the riots, Iain Duncan Smith has said.
In a Spectator interview, the Work and Pensions Secretary said the unrest was "our warning" of what will happen if reforms are not made.
Mr Duncan Smith told the magazine: "There has been a lot of focus on debt and the economic crisis. Now, we have to focus on the social crisis.
"The Prime Minister made it clear that this, now, is his big focus. It is not possible to have watched or experienced any of these riots without realising that we're in the last-chance saloon.
"This is our warning. That wasn't the crisis, but the crisis is coming.
"We can't let this go on any more, and I think the Prime Minister sees that."
He predicted that the riots would change Mr Cameron's leadership in a similar way to how 9/11 impacted on Tony Blair's premiership.
"Well, I think he sees it like that. It's been a reminder to him. He's now determined this is what he wants to do," he said.
Mr Duncan Smith added that Margaret Thatcher's government had "freed up the markets, but what was missing was the next bit".
He said that Britain "ended up with a sort of mid-20th century society, many locked away in welfarism, and a 21st-century economy".
Mr Duncan Smith was confident that gangs were at the centre of the riots after "very good evidence" showed they "were co-ordinating locations".
The former Tory leader and Home Secretary Theresa May will present a report to the Prime Minister and Parliament in October on the Government's work to tackle gangs.
He said the report would contain "a proper set of recommendations with a timescale for implementation", and will "set a template for what we believe as a national position every area should do and we'll expect that to happen".