An investigation has been launched after a member of the Australian Defence Force told police he was assaulted and threatened outside his home in Sydney's north-west.

The 41-year-old man told police he was threatened and assaulted by two men while wearing his full uniform at Bella Vista at 6.30am on Thursday.

ADF members have been advised by the Department of Defence to refrain from wearing their uniforms in public.

The man, who suffered minor bruising, reported the matter to police and then attended Kings Cross police station in person later on Thursday.

The ADF member described his attackers as being of Middle Eastern appearance.