The prime minister said he believed that marriage was "a good thing", but he said anti-social problems were not limited to single parent families.
He said specific intervention was needed to target dysfunctional families whose "kids have gone off the rails".
Tory leader David Cameron has said that absent fathers and a lack of role models was fuelling gang culture.
Following the deaths of three teenagers in south London, within weeks of each other, Mr Cameron said he backed tax breaks to help families stay together and supported promoting a "culture of responsibility and respecting authority".
At his monthly press conference Mr Blair said, when it came to the most dysfunctional families who were "shut out" of mainstream society, specific intervention was needed at an early stage.
"In my view, the debate is not about marriage versus lone parents. The debate is about how you target measures specifically on those families some of whom happen to be lone parents - but some of whom are couples."
He said it was important to support lone parents who wanted to get back into work and said Labour policies such as Sure Start and tax credits had benefited all types of families.
"Of course it is the case it is better to have kids in a stable relationship. Of course marriage is a good thing."
But he added that with the most severely dysfunctional families, their problems went "far far deeper" and required "tough measures with support at a very early stage".
Mr Blair's comments came ahead of a speech later on Tuesday in which Education Secretary Alan Johnson will say family policy must not be biased in favour of marriage - saying taxation and law does not create strong families.
"Our family policy must be bias free... it's not who or what the parents are, it's what they do," he will tell a Relate conference.
"Bias free", well in the UK the tax policy actually advantages the seperated or co-habiting couples and single parents. Giving some tax advatange to married couples would give the impression that the Government actually thinks that marriage is worth supporting.
By not supporting the family the government is presumably saying something very clearly about what it considers to be important and what it considers to be at the root of society.