Tuesday's DA march to Cosatu House suffered from a lack of adequate public order policing and protection, the party said on Thursday.
The police must explain why more public order police were not at the scene, why Cosatu supporters were not dispersed - as their demonstration was illegal - and whether any threat assessment had been conducted prior to the march, Democratic Alliance spokeswoman Kate Lorimer said in a statement.
She had written to the police requesting a meeting with the acting commissioner to discuss what went wrong and how similar situations could be avoided in future.
“It is imperative that the SA Police Service explain why they did not uphold the legal right of the DA to march,” she said.
“Did political pressure influence their behaviour?”
In her letter, Lorimer complained that the lack of public order policing preparedness and protection was unacceptable.
There had clearly been no communication between the SAPS and the Johannesburg Metropolitan Police Department (JMPD) regarding the march, she said.
“The two were badly organised, and seriously under manned and under resourced.”
It was the job of the police to uphold the law, and the DA had had a legal right to march.
“Over and over again I heard our DA marchers saying they would never trust the police again, as the SAPS were clearly biased towards Cosatu,” she said.
“It is understandable that they came to this conclusion.”
JMPD spokeswoman Inspector Edna Mamonyane said crowd control was the responsibility of SAPS.
The metropolitan police were responsible for traffic control.
SAPS spokesman Brigadier Neville Malila said: “The provincial office has not received a request for a meeting as yet.”
Malila did not want to pre-empt any discussion that would take place later.
The DA march on Tuesday, headed by leader Helen Zille, youth leader Makashule Gana, parliamentary leader Lindiwe Mazibuko and national spokesman Mmusi Maimane, began peacefully. But as the protesters turned into Jorissen Street in Braamfontein they were met by toyi-toying Cosatu members moving down the street from Cosatu's offices, opposite the Joburg Theatre.
For an hour, the two groups traded insults with a cordon of police keeping them apart.
When rocks and pieces of cement were thrown into the crowd during Zille's speech and a DA member on the VIP truck was seriously injured, the DA retreated to Jan Smuts Avenue.
Cosatu members chased DA supporters and police had their hands full trying to control groups intent on hounding the blue-shirted protesters out the area.
Police eventually sprayed teargas and fired a high pressure water gun to break up the Cosatu crowd.
Several car windows were smashed and at least two people were injured by flying bricks and rocks. - Sapa