It is believed Mr Mugabe’s party is divided over pushing for an early poll, but the president was endorsed as the party’s sole candidate at its annual conference at the weekend.
In an interview with the ABC, Mr Tsvangirai, who became prime minister under a power-sharing deal following failed elections two years ago, says promised reforms must be met before any general election is called.
And he says it would be illegal for Mr Mugabe to unilaterally set a date for new elections.
The last election saw Mr Tsvangirai’s party win the majority of seats in the parliament, but it did not emerge with enough support to prevent a run-off.
Mr Tsvangirai boycotted the presidential vote after violence swept the country and hundreds of his supporters were killed.
Mr Tsvangirai also says Mr Mugabe’s calls for new laws making it treasonable to support sanctions against the country are laughable.
Mr Tsvangirai was accused of supporting sanctions after a diplomatic cable released by WikiLeaks showed he was in the same room as American diplomats discussing sanctions against Zimbabwe.
Ever since the cable was released, Mr Mugabe has been running a campaign against his prime minister.
Mr Tsvangirai says it would not be possible for the president to implement laws making support for targeted sanctions an offence of treason.
He says it would require support of the parliament and the president does not have the numbers.
Mr Tsvangirai says targeted sanctions have been imposed by sovereign nations – something which neither he nor Zimbabwe can control.
Meanwhile, Robert Mugabe’s Zanu (PF) has threatened to expel “interfering” Western diplomats as Zimbabwe’s former sole ruling party rolls out a campaign to crush opposition to its quest to wrestle power lost in the last elections held in 2008.
In a move targeted at envoys from the United Kingdom, the United States, New Zealand and Australia, President Robert Mugabe’s party said it would not countenance any further interference by the West in Zimbabwe’s internal politics.
“The party resolves that foreign envoys who promote the West’s regime change agenda and interfere in the internal affairs of Zimbabwe be expelled,” ZANU PF said in a communiqué issued at the end of its annual conference held in the eastern border city of Mutare at the weekend.
This is not the first time Mugabe has threatened to kick out the ambassadors of “hostile” Western countries.
He issued the same threat in March 2007 after accusing Western diplomats of supporting the opposition MDC-T party led by Prime Minister Morgan Tsvangirai.
The veteran leader said at the time that diplomats who wanted to represent their countries in Zimbabwe had to "behave properly" or they would be thrown out.
He again made a similar threat in August this year when, through Foreign Minister Simbarashe Mumbengegwi, he read the riot act to the ambassadors of the UK, US, Australia, New Zealand and the European Union for walking out during his speech at the burial of his late sister in Harare.
The diplomats were also warned against their continued interaction with MDC-T officials.
They were ordered to stop visiting opposition officials and attending their court appearances and those breaking the order would face imminent expulsions.
Mugabe is particularly keen on expelling British ambassador to Zimbabwe, Mark Canning, and his American counterpart, Charles Ray, as an example of what he can do to the rest of the Western diplomats.
The two have been outspoken in their criticism of the Mugabe regime.
Observers however say the expulsion threats may be just that – mere rantings of a cornered despot who wants to portray a Macho image among bewildered supporters.
“These will remain just threats because Mugabe himself knows that such action would attract similar measures from the West, something that he is not prepared for at the moment,” said political analyst Donald Porusingazi.
Cutting off ties with the rich Western nations would be suicidal for Mugabe who is desperate to win back voters who deserted his party at the height of an unprecedented economic crisis in 2008.
“After all the political grandstanding normally associated with ZANU PF meetings, even Mugabe himself knows that completely shutting out the money-totting West would be like signing his own death certificate. Without Western backing, there won’t be any recovery of agriculture, health and education sectors to talk of,” added Porusingazi.
Western nations have always bankrolled Zimbabwe’s social sectors and the effects of their support were seen when they withdrew assistance at the height of the country’s political crisis in the mid-2000s.
The Western pullout triggered a collapse of the education sector, with an unprecedented exodus of qualified teachers and children not going to school for more than a year.
Most health facilities also closed due to lack of staff and drugs while those that remained open demanded extortionist prices before offering services.
The timing of the expulsion threats is particularly interesting as it comes at a time when ZANU PF is pushing for elections next year.
Mugabe wants to silence the envoys so that they would not comment on the cases of violence that his party is expected to unleash in the run-up to the polls.