It is the first time the South African government has joined international concern about the delay.
The EU also called for the immediate availability of the vote count, adding that a further holdup would be "unacceptable".
John Clancy, a spokesman for the EU executive, told reporters: "Clearly the publication of the results is needed and it's needed now.
"Further delays are unacceptable and would just be considered as stalling the democratic process."
Earlier on Thursday the government of Zimbabwe accused MDC leader Morgan Tsvangirai of treason and colluding with Britain, the county's former colonial power, to remove President Robert Mugabe from power.
Gordon Brown, the British prime minister, had said at a UN and African Union summit on Wednesday that no one believed that Mugabe had won the election.
Patrick Chinamasa, the justice minister, said: "It is clear from the correspondence that Tsvangirai along with Brown are seeking an illegal regime change in Zimbabwe and on the part of Tsvangirai this is treasonous.
"There are no doubting consequences for acting in treasonous manner."
Tsvangirai has said that Mugabe – who with his ZANU-PF party has led the country for 28 years - attempted to steal the elections via using a violent militia crackdown.
The Group of Eight advanced nations (G8) also expressed "deep concern" about rising tension in Zimbabwe on Thursday.
The ZANU-PF party lost control of parliament for the first time in last month's elections, but the presidential vote results are yet to be announced.