Workers had been set to strike after threats of 100 job cuts by management.
A statement from Euro Packaging said the cuts were still being considered due to a downturn in demand and an increased cost base.
GPMU deputy general secretary Tony Burke said the packaging firm had threatened to move work from the UK, and initially refused to co-operate on union recognition.
Talks will now take place between the GPMU and management with regards to the selection criteria for redundancies, health and safety issues and the movement of equipment.
GPMU national industrial officer Peter Ellis said industrial action had only been suspended in line with current legislation, and could be reinstated at any time within a 28-day period.
The union is also seeking agreement on a full collective bargaining agreement at the plant, which Ellis said remained a separate issue.
An overwhelming majority of the 170 Sparkbrook-based workforce had opted to join the union, which prompted threats from management at the plant.
"Our members along with ACAS tried to negotiate, but every time we took one step forward we took two back," said Burke. He said the firm had been looking for confrontation rather than consultation using the threat of job losses.
Workers had opted to join the GPMU following a campaign to seek union recognition.
Story by Andy Scott