Tsvangirai told a stormy audience of 1,000 people in Southwark Cathedral that "Zimbabweans must come home," but they said that 85-year-old President Robert Mugabe must quit first.
Failing to make himself heard above the boos and chants of "Mugabe must go," Tsvangirai left the pulpit for two minutes before returning to face questions.
He said, "I did not say ‘pack your bags tomorrow,’ I said ‘you should now start thinking about coming home’."
Boos also rang out when Tsvangirai insisted that the four-month-old unity government of his Movement for Democratic Change (MDC) and Mugabe’s ZANU-PF had "made sure that there is peace and stability in Zimbabwe."
Many people shouted "not yet".
In a question and answer session, some exiles asked Tsvangirai what the government was doing to help Zimbabweans who had been "traumatised" by violence.
He said: "If there is anyone who has been traumatised, it is me."
After briefly answering several more questions, a shaken-looking Tsvangirai was ushered away by his bodyguards amid a fresh hail of boos.
One exile in the crowd, Alex Chigumira, 42, who fled Zimbabwe eight years ago, said: "We can already see that Tsvangirai has adopted the politics of Mugabe.
"He is unrealistic. What he forgets is that people here are traumatised, that is why they are in Britain.
"I do not think I would return to my country while Mugabe is still in power."
Nyasha Muzambi, 33, said: "Mugabe is the reason we fled the country. When he goes, we will come."
In an interview on Saturday with the Daily Telegraph, Tsvangirai said he had an "extraordinary" working relationship with Mugabe, his one-time bitter enemy.
Tsvangirai insisted that the veteran president — who previously tried to crush the MDC — was "an indispensable, irreplaceable part of the transition".
"It is a workable relationship, surprisingly. Yes, I am actually surprised. Who would have thought that sworn opponents like us could sit down and talk about what’s good for Zimbabwe? It’s an extraordinary experience," he said.
London is Tsvangirai’s final stop on a tour of Europe and the United States to drum up support for the ‘new’ Zimbabwe.
Britain has sounded a cautious note, saying it will support the inclusive government despite its concerns about Mugabe but that it will not lift sanctions until Harare proves it is on a path to democracy.
Amnesty International said this week that Zimbabwe was suffering "persistent and serious" human rights violations despite the formation of the unity government.
Tsvangirai is expected to hold talks with British Prime Minister Gordon Brown on Monday.