In a fiery speech on Friday, Mugabe, 84, criticised party indiscipline and defied calls from several leaders to step down as he addressed supporters with a first-ever parliamentary majority loss hanging over the party.
"If we are not united, the party is weaker," Mugabe told thousands of delegates at the party's 10th annual conference.
"Some said don't vote for the president. This was a contest between various parties and if your presidential candidate lost it meant you lost as a party," he said, pointing to the country's March polls.
Mugabe then returned to the kind of defiance he has often shown in the face of mounting criticism.
"I will never, never, never, never surrender. Zimbabwe is mine, I am a Zimbabwean. Zimbabwe for Zimbabweans. Zimbabwe never for the British, Britain for the British," he said.
Collapsed economy, eye-popping inflation rates
The meeting comes as the party comes under mounting international pressure amid a ruinous political crisis, a deadly cholera epidemic and failure to implement a power-sharing deal signed three months ago.
The UN says more than 1 100 people have died in the cholera epidemic, adding to woes such as food shortages and poverty as Zimbabwe struggles with a collapsed economy and eye-popping inflation rates.
Mugabe's speech came after rival Morgan Tsvangirai threatened to quit deadlocked unity government talks over the abductions of more than 42 members of his Movement for Democratic Change (MDC) party and civil society.
Zimbabwe's opposition leader, who should become prime minister when a unity accord is finally implemented, warned of a long list of outstanding issues with the veteran president before the new government could be set up.
Mugabe said that he had invited Tsvangirai and fellow opposition leader Arthur Mutambara to be sworn in, but said he did not know if the inclusive government would work.
Mashonaland Central governmer Martin Dinha earlier told delegates that Zanu-PF would not have entered talks with the MDC if it had not gone into the elections divided.
"The lessons learnt after the March 29 elections must not be forgotten," said Dinha in his opening remarks on Friday, quoted in the state-owned Herald.
"We lost our majority in the parliament as some of us put petty issues and self interests ahead of the party.