Cape Town officials criticised the PPA security firm for last Sunday's incident, in which black beachgoers were allegedly ordered to leave the beach at Clifton, an upmarket coastal suburb.
The eastern city, where beaches, like many public areas, were segregated under white-minority apartheid rule, remains a flashpoint of racial tension in the rainbow nation.
Friday's demonstration at Clifton Beach was organised by a lobby group known as the Black People's National Crisis Committee.
Political activist Chumani Maxwele, best known for his involvement in Rhodes Must Fall Movement, is one of the leaders of the movement.
Speaking to RFI from the beach, he denounced Cape Town officials for working with those he called "racists" holding sway in the Clifton neighbourhood overlooking the beach.
The city's mayor and a senior municipal official denounced the PPA firm and dismissed claims it was working for the city authorities.
Maxwele dismissed claims that blacks were being chased away to protect local residents from criminal activity.
“There has never been any crime there,” he notes, adding that locals simply see black people as criminals – which he says is a stereotype dating back to the apartheid era.
Maxwele spoke bitterly about the plight of black hawkers working at the Clifton beach claiming they are being mistreated by white residents who think they own the place.
He also expressed the determination of the activists to hold a cleansing ceremony for their ancestors who died at the beach and end the racism perpetuated against black people.
As the controversy over the privatisation of the Clifton beach grows, the private company at the center of the lock down announced it had decided to end its patrols.
Cape Town City’s head of safety and security has reportedly issued a release stating that the Council neither has a contract with the PPA firm nor given it any authority to enforce by-laws.