The African Union has urged Zimbabwe to respect democratic principles and human rights as the political crisis in the country deepens.
African leaders have been reluctant to criticise Mr Mugabe
In a statement, the pan-African body also called for a "constructive dialogue" to resolve Zimbabwe's issues.
Western criticism of Robert Mugabe's government was heightened after the main opposition leader was beaten.
But until now African leaders have been reluctant to publicly speak out against Mr Mugabe's regime.
The statement said the AU commission chief Alpha Oumar Konare had been watching events in Zimbabwe with "great concern".
"He urges all concerned parties to commence a sincere and constructive dialogue in order to resolve the problems facing Zimbabwe," the statement said.
Mr Tsvangirai said Zimbabweans were ready for confrontation
Meanwhile the authorities in Zimbabwe have stopped two senior opposition officials from leaving the country for medical treatment.
Sekai Holland and Grace Kwinje, from the Movement for Democratic Change (MDC), were among activists beaten in police custody after being arrested at a political rally in Harare last week.
They were prevented from boarding a flight to South Africa, and are now back in hospital in Harare, under police guard.
The leader of the MDC, Morgan Tsvangirai, who was also beaten while in police custody following the rally, left hospital on Friday. Four of his colleagues remain in hospital.
On Saturday Mr Tsvangirai told the BBC said that the people of Zimbabwe were ready to confront Mr Mugabe's government.
"We know that people are resilient in spite of the brutal response by this regime," he said.
"People are determined to confront the regime in any way possible so I'm very positive that the people of Zimbabwe are not going to lie low and submit."
His comments were echoed by fellow MDC leader, Arthur Mutambara, who said that Zimbabweans were ready to drive Mr Mugabe from office.
"If there is going to be any war, this is the time to declare war," he said, adding that they aimed to achieve their goals by "democratic means".
UK Foreign Secretary Margaret Beckett has said she holds Mr Mugabe personally responsible for Mr Tsvangirai's injuries.
The British envoy to the UN called for the Security Council to be briefed on developments in Zimbabwe.
But South Africa, which holds the council's rotating presidency, has made it clear that the body will take no action against the country.
It maintains the crisis in Zimbabwe is no threat to international peace and security.
Mr Mugabe has rejected the criticism and blamed the opposition for instigating the violence.
Addressing the youth faction of his party on Friday, the 83-year-old threatened to kick out diplomats if they dared to attend opposition meetings.
He also warned his political opponents: "If they do it again, we will bash them again," he said.
Mr Mugabe has ruled Zimbabwe for 27 years, but there is increasing discontent over the country's economic crisis.
More than 80% of Zimbabweans are living in poverty, with chronic unemployment and inflation running at more than 1,700% - the highest in the world.