The Economic Freedom Fighters in the Western Cape said it would approach the police and the South African Human Rights Commission on Tuesday following the display of the old South African flag at a recent protest.
Demonstrators marched to Parliament on Sunday to call on government to prioritise violent crime, specifically in rural and farming communities.
However, the EFF said the appearance of the apartheid era flag undermines the law and the injustices suffered in the past.
One demonstrator was seen donning a hat with the old apartheid-era flag on it and another was waving the Zuid-Afrikaansche Republiek flag.
The EFF said those who displayed flags representing the apartheid-era should be held to an account.
The party is also calling for the arrest of the protest organiser and Agriculture MEC Ivan Meyer who addressed the crowd.