Two men have been charged after allegedly attempting to kidnap a woman in Sydney's south-west yesterday.

One of them allegedly assaulted a 27-year-old woman after she stopped to change her car's flat tyre on Browne Parade in Warwick Farm near Liverpool yesterday afternoon.

Police will allege that one man allegedly threatened the woman with a knife before attempting to drag her towards a Kia SUV.

However, bystanders intervened and he was forced to flee in the car.

Paramedics treated the woman for injuries to her face and leg, before she was taken to hospital.

Police subsequently arrested two men - one 22-year-old on the riverbank of Duck Creek in Auburn, and a 24-year-old on West Street in Auburn.

It is alleged the men were waiting for the woman in a Liverpool car park before following her car to Browne Parade.

They were taken to Granville Police Station where they were charged with robbery armed with an offensive weapon, and aggravated robbery and use of corporal violence.

Both men were refused bail to appear in court today.