Monday's move came as the Health Services Union (HSU) called for better training and tougher powers for hospital security staff, following a punch-up at the Royal Prince Alfred Hospital on Sunday evening.
Police say an argument broke out between two women that quickly escalated to a violent brawl involving as many as 20 people.
HSU secretary Gerard Hayes said one security guard who tried to intervene was held down in a headlock and punched repeatedly by three men, while a nurse was dragged by her hair.
The hospital's general manager Deborah Willcox has told AAP the family involved will now be restricted to visiting their relative in pairs only.
"We met with the family today; it was obviously a very distressing incident for all involved, and we've put some restrictions around their visiting just to ensure that we minimise the chance of anything like this reoccurring," Ms Willcox said.
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"Our main concern is obviously for the patient and their wellbeing, and obviously to the rest of the patients and families who are on this ward.
"We don't want them to be exposed to this type of event again."
She said hospital staff and police "handled the situation impeccably".
Both security guards and the injured nurse were off work on Monday.
"I understand they're all okay and I'm hopeful they be back at work very, very soon (but) they'll have as much time off as they need," Ms Willcox said.
AAP understands the riot squad stepped in to assist because a squad car was near the hospital at the time the violence erupted.
The HSU's Mr Hayes said it was not acceptable for hospital security staff to be forced to rely on police intervention to keep health workers and patients safe.
"It's now time for the government to stand up and ensure that the appropriate health security is in place to ensure that these things don't happen," he told reporters.
He wants Health Minister Jillian Skinner to empower health security workers to restrain patients.
A spokeswoman for Mrs Skinner told AAP the minister had been made aware of the incident on Monday.
