Matthew McConaughey (AP)

Matthew McConaughey angrily confronted a paparazzo after a triathlon in Malibu, California when the over-eager snapper got too close to the actor's newborn son Levi.

The Fool's Gold star took part in the gruelling event on Sunday, running, swimming and cycling his way through the tough endurance race alongside new mum Jennifer Lopez.

After completing the race, McConaughey was congratulated by his girlfriend Camila Alves who had been cheering him on from the sidelines while holding their tot.

But the star soon lost his temper with a photographer after he began to follow the pair along the beach, upsetting Alves by taking snaps up close.

In a video posted on TMZ.com, McConaughey can be seen approaching the snapper, telling him to "back off" several times.

It is not the first time the actor has had trouble with photographers in Malibu - two local surfers were charged with battering a paparazzo who got too close to the star while he was riding the waves.