A320 Captain reported a traffic conflict with ground vehicles not yielding to the aircraft when beginning to taxi on the ramp. The First Officer called out the moving trucks to the Captain; who applied the brakes as the vehicles passed in front of the aircraft.

Narrative

We were pushed back off of Gate XX and tug disconnected us at Spot 1. I flashed our taxi light to the ground crew and received our salute from them. We configured for single engine taxi and ran the after start start checklist. FO (First Officer) called ramp for taxi and we were told to exit through Spot XX. I turned on the taxi light after clearance was received; visually cleared left and ahead while verbalizing it and also scanning to the right. Saw 2 construction pickup trucks stopped at the edge of the vehicle road waiting to make a right turn which would cross directly in front of us. FO visually and verbally cleared right and ahead. I advanced the left throttle to start taxi and FO said to wait; the trucks were now moving. I immediately brought the throttle to idle and applied brakes as I saw the 2 construction pickup trucks pass in front of us from right to left on the service road; just visible over the nose of the aircraft. I flashed the taxi light multiple times at them as they drove by.