Three men, including a serving New South Wales police officer, have been charged over an alleged robbery attempt in Sydney's south-west.

Heavily armed special tactics officers swooped on the trio about 10:30am on Monday on a busy stretch of road in Cabramatta.

It happened after two men, wearing wigs and fluorescent work shirts, allegedly tried to rob a woman as she exited the Vina Money Transfers shop on John Street.

They allegedly used capsicum spray on her and two men she was with.

Police had the men under surveillance and stepped in, capsicum spraying and subduing them just as the alleged robbery was about to take place.

In a statement, police said the alleged robbery attempt "did not involve firearms".

One person was injured in the police operation, which was run by the Professional Standards Command and the South West Metropolitan Region Command.

It is understood the police officer in custody was a member of a south-west regional enforcement squad who had recently been suspended without pay.

On Monday night, the three men, all aged 29, were charged with armed robbery in company and three counts of stealing.

They were refused bail and are due to appear before the Liverpool Local Court on Tuesday morning.