Mugabe and Tsvangirai signed a broad power-sharing deal brokered by South Africa’s former president Thabo Mbeki on September 15 but the agreement has since stalled over who should run which ministries.
Tsvangirai, who is set to become prime minister if the power-sharing government takes off, also said Zimbabwe badly needed a political settlement to address a dire economic crisis that had given left millions of people hungry.
"We want to see a finality to this issue," he said, adding that nobody would force him into joining an administration in which the government would have responsibilities but no power.
"We are committed to the agreement that we signed on September 15 but it is not some unconditional commitment," he said in an address delivered both in English and the local Shona language.
Tsvangirai says Mugabe is trying to seize important ministries and sideline his opposition Movement for Democratic Change (MDC), told a rally on Saturday he hoped a regional summit on the issue in Harare on Monday would solve the problem.
"Our commitment is to an equitable power-sharing arrangement otherwise we are not going to be part to it and we may as well look for alternative political options," he said, adding:
"When it comes to negotiations, no one is to bully us."
Tsvangirai boycotted a mini summit of the Southern African Development Community (SADC) in Swaziland last Monday, citing Harare’s refusal to give him a new passport instead of the emergency travel document he got for the trip.
On Saturday, the MDC leader said his party had high respect for SADC and the African Union, and wanted the Zimbabwe crisis to be solved by Africans.
"We have very serious respect for SADC and the AU but they must reciprocate that respect. We don’t want the (Zimbabwe) issue to go outside Africa," he said, hardly a week after his party suggested the United Nations should intervene.
But Tsvangirai warned against Mbeki’s quiet mediation style.
"We respect Mbeki but quiet diplomacy has its limits if it leads to quiet approval of wrong things," he said.
Tsvangirai said Zimbabwe needs to reach a deal quickly to turn its attention to food shortages and an inflation that had soared to over 230 million percent.
"People are starving around the country, scrounging. Some are competing with baboons for wild fruits," he said of food shortages.