St John Ambulance spokesman Ian Henderson confirmed ambulance officers were called to Mega Air in the suburb of Hornby just after 6pm last Monday.
A boy aged in his mid-teens was taken by ambulance to Christchurch Hospital with serious injuries, Henderson said.
A Worksafe spokesman said they had been notified of a person suffering a "spinal injury" at Mega Air last Monday. Worksafe staff were making preliminary enquiries before deciding whether to investigate further.
No prohibition notices had been issued, the spokesman said.
It is not known how the boy was injured.
In a statement, Mega Air Trampoline Arena director Matthew Haselden said the operation
had robust health and safety measures in place.
"Every customer is required to follow rigorous safety precautions and take part in a safety induction, which includes viewing a health and safety video.
"There are also between 5 and 11 jump guards plus a duty manager; supervising the facility at all times with senior jump guards certified St John first aiders.
"Real-time video footage allows staff to watch, review and assess safety at all times."
Haselden said Mega Air was the country's biggest trampoline centre. It opened on August 16 this year and more than 31,000 people had visited the centre since.
"We are very upset that this injury has occurred and we have been in regular contact with the boy's father to offer support," Haselden said.
"What happened last week appears to have been a freak accident."
The company had contacted WorkSafe which visited the site last week and advised Mega Air that the foam pit, in which the injury took place, met health and safety requirements and could re-open.
"However, as per plans set out three months ago, the foam pit will be replaced with an air bag this week, which is why the foam pit is currently closed."
During the development of the centre, nearly $1 million was spent ensuring the facility was safe for public use, he said, with more than $500,000 used to put specific health and safety measures in place.
Before opening, a full compliance test was carried out by Consulting Engineers from NZ, Haselden said.
A post on Mega Air's Facebook page the day following the incident states that the foam pits had been closed "in preparation for the arrival of a BRAND new Air bag!".
As well as the extensive trampoline areas, the park also has at least two sponge pits.
The main pit is described on Mega Air's website.
"Five trampoline launch pads allow you to catapult into a 9 metre sponge pit filled with thousands of gymnastic grade foam cubes. You can practise your aerial moves before you have a soft landing in the sponge pit.
"For safety's sake, we do not allow diving or landing head first and only allow a single jumper at a time."