Troops have been out on the streets trying to prevent unrest
Ethiopian Prime Minister Meles Zenawi has said he regrets the deaths of at least 46 people killed in last week's anti-government protests.
But he said it was understandable that police had panicked when facing protesters with hand grenades and guns.
Speaking in Germany, Mr Meles accused the opposition of provoking unrest.
The opposition has called a week-long strike from Monday. A BBC correspondent in Addis Ababa says the police are braced for more possible violence.
The unrest first erupted on Tuesday after the opposition accused the government of rigging the 15 May elections and there are fears of more protests.
The elections saw Mr Meles's Ethiopian Peoples Revolutionary Democratic Front take control of two-thirds of the country's parliament.
After the clashes, many opposition leaders were detained.
"We regret the death but it was not a normal demonstration," Mr Zenawi said during a visit to Bonn.
"And I don't want to justify it when policemen get in a panic, but I can understand it when there are people throwing hand grenades and using guns," he said.
Mr Meles had earlier announced that an independent commission would investigate whether police had used excessive force to quell the unrest.
Ambassadors from 21 countries which have given aid to the drought-ravaged country issued a statement expressing dismay at the violence, and calling for an urgent investigation.
On Sunday, a joint statement by the US and the EU called on all political parties to "desist from further violence and to abide by the rule of law".
Last week, the unrest erupted in the towns of Bahir Dar, Awassa and Debre Berhan.
It was the worst disturbance in sub-Saharan Africa's second most populous country since protests first ignited after the elections, when some 36 people died and hundreds were arrested.
Police and soldiers have been patrolling Addis Ababa but residents fear the outbreak of more violence.
The unrest has sparked fears the country may be moving into a period of more authoritarian rule.
The internal crisis comes at a time of increasing tension with Eritrea over the two countries' disputed border, our correspondent says.