"The MDC's position is that Morgan Tsvangirai was giving a warning to President Mugabe to consider history. There is a long line of dictators who have refused to go peacefully - and the people have removed them violently," he said.
The Movement for Democratic Change leader told 20,000 supprters at a rally on Saturday that if Mr Mugabe did not want to step down before the next elections scheduled for 2002 "we will remove you violently".
On Monday, state news agency ZIANA quoted police spokesman Wayne Bvudzijena as saying police were examining Mr Tsvangirai's speech with a view to establishing grounds to charge him.
On Sunday, Zimbabwe's ruling party warned the MDC that it would respond with violence to any attempt forcibly to remove President Robert Mugabe from office.
Increasing tension
MDC secretary for legal affairs David Coltart said that Mr Tsvangirai had no legal case to answer.
"The MDC's position is that Morgan Tsvangirai was giving a warning to President Mugabe to consider history. There is a long line of dictators who have refused to go peacefully - and the people have removed them violently," he said.
Our correspondent in Harare says that Mr Tsvangirai's comments reflect an increasing desperation on the part of many Zimbabweans as they watch the economy continue to disintegrate after months of political instability.
In the run-up June's parliamentary elections at least 31 people died - mostly MDC supporters. The MDC won 57 seats in parliament ending Zanu-PF's virtual monopoly on power since independence in 1980.
However, tension between the opposition and ruling party has remained high since then.
Last week the MDC said a recent grenade attack on its hq was the work of a police agent, but the government alleged that the MDC itself was behind the attack.