Brigadier Hangwani Mulaudzi said they were there to support Malema ahead of an announcement of his fate within the party.
"Police started monitoring the situation around 14:00. By then there were about 200 people. The number has now swelled to about 500 people," he said.
"We have police on the ground, and there have been no incidents."
African National Congress spokesperson Keith Khoza said the party's national disciplinary committee (NDC) was scheduled to make an announcement on Malema's mitigation hearing on Wednesday.
"As far as I'm concerned, the announcement will still be made today [Wednesday] as announced by the NDC earlier though a statement. We haven't heard anything to the contrary," Khoza told Sapa.
Khoza said the committee was still inside ANC headquarters Luthuli House, in Johannesburg.
"We are also still waiting," he said.
According to a statement issued by NDC chairperson Derek Hanekom on Wednesday morning, Malema's mitigation hearing announcement would be made in the "late afternoon".
Nothing had been heard by 8pm. By this time, many journalists who had been waiting outside Luthuli House from as early as 14:00 started leaving.
Malema was reportedly in his hometown of Seshego, Limpopo. His legal team had also reportedly not formally received the decision, raising doubts that the NDC would release its findings on Wednesday.
The ANC's constitution requires the NDC to first inform Malema of its decision before handing over formal documentation to ANC secretary general Gwede Mantashe. Only then it may announce the findings to the public.
Malema's lawyers, Patrick Mtshaulana and Dali Mpofu, refused to comment on matter. Mtshaulana said he "was at court the entire day" and heard about the expected announcement on radio news on his way home.
Policemen were earlier stationed at the door to the ruling party's headquarters. The streets surrounding Luthuli House remained open to traffic, and there was no sign of Malema supporters. Journalists were ordered not to stand near the building and told to go across the road. Parked at the corner of the building, on Sauer Street, was a police van and a Nyala.
On February 4 the African National Congress's national disciplinary committee of appeals announced it had upheld the conviction of Malema and five ANCYL officials for bringing the party into disrepute and sowing divisions in its ranks.
Malema was suspended for five years. League spokespersonFloyd Shivambu, deputy president Ronald Lamola, treasurer general Pule Mabe, secretary general Sindiso Magaqa and deputy secretary general Kenetswe Mosenogi were suspended for periods ranging from 18 months to three years.
Their appeal against their sentences was dismissed. They were then allowed to present evidence in mitigation. The sentences were suspended pending the outcome of this hearing.