"Let me clarify, we have not withdrawn from government, we are still in government," Tsvangirai, head of the MDC party, told journalists after meeting with Angolan President Jose Eduardo dos Santos.
The latest crisis to hit Zimbabwe’s unity government was sparked by the arrest and trial of a top MDC official, who faces treason charges, and by Mugabe’s failure to appoint senior government officials, including a central bank governor.
As a consequence, Tsvangirai last week said MDC would disengage from the unity cabinet set up in February.
Tsvangirai arrived in Luanda to seek advice from dos Santos in dealing with Mugabe and ZANU-PF, which he accuses of being dishonest.
"We have disengaged with the party that is a coalition with us, which is ZANU-PF, over matters that are critical to the credibility of the inclusive government," Tsvangirai said.
Earlier in the week, Tsvangirai met with the Democratic Republic of Congo President Joseph Kabila and South African President Jacob Zuma in a bid to increase regional pressure on Mugabe to work with the MDC.
"President dos Santos is one of the senior leaders in the region, he together with others was instrumental in crafting this political dispensation," said Tsvangirai.
Tsvangirai and Mugabe entered the unity government after two violent and widely disputed elections left the impoverished African state in a stalemate and in danger of serious violence.
Neighbouring countries in the Southern African Development Community (SADC), led by South Africa, helped broker a deal, but the resulting government has been plagued by problems and setbacks from the start.