They tore pictures of Mr Mugabe and marched to his office and residence.
The army intervened on Wednesday, days after Mr Mugabe sacked his deputy, signalling that he favoured his wife Grace as his successor.
Mr Mugabe, who is confined to his house, was to meet army chiefs on Sunday, state TV said. The 93-year-old has led Zimbabwe for 37 years.
The military says it will advise the public on the outcome of talks "as soon as possible".
Saturday's rally had the support of the army and members of the governing Zanu-PF party.