The delegation began talks in Harare, Zimbabwe's capital, just weeks after Tsvangirai announced a boycott of the cabinet.
Tsvangirai's Movement for Democratic Change (MDC) described as "arrogant" a refusal by Mugabe to fully implement the power-sharing agreement, which led to the creation of the prime ministerial position.
Sadc, a 15-member bloc, has been involved in a search for a solution to Zimbabwe's governance problems and is credited with brokering a coalition in February between Mugabe and Tsvangirai.
The ministers from Mozambique, Swaziland and Zambia, support staff from the Sadc secretariat and representatives of Thabo Mbeki, a Sadc mediator and former South African president, have been meeting Zimbabwean officials over the past two days.
"We are listening to the issues and the views being raised by the two parties, and we are counselling all of them ... that it is important that they should remain engaged in the interest of the people of Zimbabwe," said a Sadc official.
"Sadc is ready to help the Zimbabwe parties to reach an understanding on those matters where they have differences."
It was not immediately clear how the negotiations progressed, but analysts said there were slim chances of a breakthrough as Mugabe's Zanu-PF and the MDC remain at loggerheads over some aspects of their power-sharing pact.
The MDC says Zanu-PF has blocked the swearing-in of some of its officials.
Ayesha Kajee, director of international human rights exchange at Witwatersrand University in South Africa, said that the ministerial delegation is "not going to have much effect".
Speaking to Al Jazeera on Friday, she said there were reports that Joseph Kabila, the chair of Sadc and president of the Democratic Republic of Congo (DRC), was heading to Zimbabwe to try to break the impasse.
"Seeing that one of the ministers is actually from a country [Swaziland] that doesn't have a very good democratic record of its own, has led analysts to predict that this won't have much effect on the impasse in the government of national unity," Kajee said.
Zanu-PF and the MDC signed a power-sharing deal in September last year after a crisis that followed disputed elections and political violence.