David Cameron and wife Samantha have three children
David Cameron has said that although he was a "great believer in the naughty step", it was sometimes necessary for parents to smack their child.
Mr Cameron, who has three children, told ITV's This Morning: "Obviously you try to do everything else.
"But if you have got a child that is just about to dash across the road, sometimes you have to grab them - and that happens quite a lot."
The Conservative leader is campaigning for more responsible parenting.
Helen Newlove, whose husband Gary was kicked to death by a gang of youths outside his Warrington home, had earlier joined Mr Cameron for his summit on Strengthening Families.
At that conference, Mrs Newlove called for action on Britain's "yob culture", blaming a breakdown in morals among some families.
Mr Cameron told the conference that getting parents to take proper responsibility for their children was the "task for a generation".
"We need to build stronger families and more responsible communities, so that kids grow up knowing the difference between right and wrong.
"Most important of all, parents need to take the responsibility of parenthood seriously."
The Tory leader then joined Mrs Newlove on the This Morning sofa to talk about responsible parenting.
Asked if he smacked his own children, Mr Cameron said he was a "great believer in the naughty step" - a reference to discipline techniques advocated by television parenting programmes and presenters such as Jo Frost - and "setting clear boundaries".
But he added: "I don't think you should ban smacking."
On school discipline, he said: "Teachers should be using much cleverer ways of disciplining children, rather than, perhaps, what some of us had at school."
Supernanny Jo Frost advocates use of the 'naughty step'
But he said the "no-touching" rule that operates in some schools, preventing any contact between teachers and pupils, was "nuts".
"We just need a return to some common sense and trust," said Mr Cameron, who was the shadow education secretary before being elected Tory leader.
"We train teachers and we have got to have some trust in their professionalism and judgement."
The Labour government introduced a partial ban on parents smacking their children in 2005, but rejected calls for a full ban.
In 2006, then Prime Minster Tony Blair told the BBC he had smacked his three older children but not his youngest, Leo.
Current Prime Minister Gordon Brown, who has two young children, has never commented publicly about smacking.