William Bango said that Tsvangirai, the leader of the Movement for Democratic Change (MDC), had been questioned at a police station for around two hours about an alleged assault that took place in the town, where a by-election is to be held at the weekend.
Tsvangirai, who is on trial for treason over an alleged plot to assassinate President Robert Mugabe, was later released without charge, Bango said.
"They (the police) questioned him in a normal way. After that, they said he could go," Bango said by telephone from the city.
Bango said a man had gone to the police station earlier claiming to have been assualted by an MDC supporter "at a place that Tsvangirai had passed through".
"We were told by the police before we left town that we were needed at the police station," the spokesperson said.
"We didn't witness the assault ourselves".
Police were not immediately available when contacted for comment.
Political tensions are rising in Kadoma ahead of a by-election due at the weekend, pitting MDC supporters against those of the ruling Zimbabwe African National Union - Patriotic Front (Zanu-PF).
Yesterday, Tsvangirai had been meeting constituents in the city, located some 140 km southwest of Harare, drumming up support for the MDC candidate, Charles Mpandawana.
The by-election is taking place after the previous legislator, who was also an MDC member, died in August.
Tsvangirai, who early this month began a landmark court challenge to Mugabe's victory in last year's presidential election, faces treason charges along with two other senior MDC officials.
The long-running trial, which started in February this year, is currently in recess.
State lawyers have argued that Tsvangirai, who attended a meeting in Canada in December 2001 with political consultant Ari Ben Menashe, allegedly requested Mugabe's elimination ahead of the elections last year.
The black and white videotaped evidence of that meeting produced in the Harare high court has been described as grainy, and only partially audible.
Tsvangirai denies the charges, which carry the death penalty on conviction, saying he was set up by government agents in a smear campaign ahead of the elections.
The opposition leader faces a second charge of treason for allegedly inciting his supporters to overthrow the government in June this year.
That trial is due to start next year. – Sapa-AFP.