A door lock assembly includes a press button disposed within an inner drive tube and an inner handle. A cam mechanism is provided to associate with the press button and the inner drive tube to rotate the press button when the press button is pressed axially. The cam mechanism includes an inclined cam groove/slot which is formed in one of the inner drive tube and the press button and which extends substantially in a helical direction, and a cam protrusion formed on the other one of the inner drive tube and the press button and extending into the cam groove/slot. A press button rod is connected to the press button for simultaneous rotation with the press button.