Cops were unable to explain how 27-year-old Mr Macia, a Mozambican immigrant, died when he was found dead in his cell two hours later.
The arrest was filmed on a mobile phone as dozens of onlookers watched in horror.
The video, which first appeared on South Africa’s Daily Sun website, shows officers overpowering their victim and knocking him to the ground.
The taxi driver’s distraught family said all he had done was argue with the police over an alleged parking violation.
The incident comes after South African police officers shot and killed 34 striking workers at the Marikana mine in August last year.
It also occurs as the country’s criminal justice system is under intense international scrutiny thanks to the high profile Oscar Pistorius murder trial.
Mr Macia was arrested at a marketplace in the Daveyton township outside Johannesburg at 6.50pm on Tuesday.
According to witnesses had been beeping his taxi’s horn to attract passengers when police arrived.
“They handcuffed him to the back of the van and slammed the door in his face. With blood running down his face they drove off.
“He was in pain, he cried and asked the cops to stop but they continued anyway.”
South Africa’s police watchdog is looking into the death and said the man was arrested because his taxi was obstructing traffic.
Spokesman for the Independent Police Investigation Directorate, Moses Dlamini, said: “We are investigating an incident involving the death of man, allegedly at the hands of the police. We are shocked by the footage which has been released.
“The circumstances surrounding his death are still allegations … let’s find out what really happened,” he said.
