A300 First Officer reported safely returning to departure airport after experiencing low pressure in the Green hydraulic system.

Narrative

The aircraft was previously written up for excessive hydraulic quantity in the Green system for which Maintenance documented that the system had been serviced prior to our arrival at the aircraft. Just after takeoff; we got an ECAM for a Green Hydraulic System Low Pressure situation and the gear would not retract. The Captain; who was currently the PF; declared that he'd keep aircraft control along with the radios and directed me to accomplish the ECAM items. Once the ECAM was completed; the Captain leveled the aircraft; [advised ATC]; requested a return to ZZZ and coordinated for a holding pattern so we could burn down fuel. We input the hold into the FMS; completed all quick return items along with applicable checklist items; contacted flight control; and briefed the approach. I sent an ACARS message to Dispatch noting the nature of the situation and our intent to return to ZZZ but received no response throughout the remainder of the flight. While we initiated divert on the FMC; we never received nor initiated the Amended Release for the return. Once below maximum landing weight; the Captain flew the approach and landing with no significant aircraft issues on approach or on the ground. The assistance was terminated once we taxied clear of the runway and determined we could taxi to parking.