Tarneshia Widders was in the midst of an anxiety attack when she was approached by police in Redfern last Thursday night.
Video of the arrest, taken by a bystander, show the 19-year-old Anaywan and Birripa woman being questioned and becoming more and more distressed.
Ms Widders said police grabbed her and pushed her into a fence.
Her partner Lili Bayles is seen in the video trying to comfort Ms Widders before being pulled away from her.
Ms Bayles video called her mother, Yarraka Bayles, during the arrest.
Yarraka Bayles told NITV News it was distressing to watch as the incident unfolded.
"I see these police officers, two male police officers on my daughter-in-law and I saw my daughter getting chucked to the ground," she said.
"I just felt so helpless as a mum, trying to keep calm and de-escalate and make sure the girls were okay.... I was just so frustrated.
"There was nothing I could do to help my daughter and her partner at that time and I thought, 'are they going to be okay?'
"There's situations like this where our mob have lost their lives way too many times, just for being black in a public place. That was their only 'crime' - walking around, being black."
NSW Police said Ms Widders spat towards them and told them she would run away. They said they pushed her back and restrained her as a result of her behaviour, and called for back-up.
Six more police officers surrounded the young women., but NSW Police said the two male officers had called for female officers to come to talk to Ms Widders.
'Take a stand'
The National Justice Project's George Newhouse, who is representing Lili Bayles, said her family wanted to see the officer's actions investigated.
"They're calling for those officers to be disciplined and for the matter to be referred to the DPP to see whether charges are appropriate," he said.
"The law enforcement conduct commission needs to investigate this kind of behaviour and the police need to take a stand and own up to this kind of conduct."
Mr Newhouse said the footage shows how distressed the young women are.
He said police are ill-equipped to be the first responders to mental health crises.
"Police should be trained to identify whether people are in a mental health crisis and de-escalate them, avoid escalating the situation and re-traumatising people," he said.
"What you've seen here is totally contrary to what should have happened."
Tarneshia was searched by police and was released without any charges.
Yarraka Bayles said the girls are still shaken by what happened.
"There was no justification for this, they weren't doing anything wrong," she said.
"If they had done anything wrong, or if they had anything on them, why weren't they charged?
"They were let go, no questions asked, no apology, no nothing so this whole ordeal has shaken us all up.
"...They're going to need a lot of support to help get through this."