A total of 40 Citizen Coalition for Change (CCC) activists have been arrested.
CCC spokesperson Fadzayi Mahere confirmed the arrest.
"I can confirm that 40 CCC members have been arrested following our roadshow in Machipisa earlier today," she said.
Mahere said the group is being represented by attorney Kudzai Kadzere.
They are currently detained at Glenview 1 police station.
Police spokesperson, Paul Nyathi said the 40 breached peace regulations.
"The Zimbabwe Republic Police confirms the arrest of 40 Citizen Coalition for Change (CCC) activists in Machipisa this afternoon for contravening provisions of the Maintenance of Order and Peace Act, Chapter 11:23 (MOPA).
"Circumstances are that the CCC convenor, Lawrence Materege notified the local Regulating Authority for Harare South on their rally set for Churu Farm on 15th August 2023 from 1000 hours to 1600 hours.
"The convenor and Grandmore Hakata then decided to divert from the notified rally at Churu Farm and went on a car rally procession from Glen View area into High Glen Road, Main Street, Machipisa Road into Highfield suburb and stopped at the OK Machipisa traffic lights while openly blocking traffic," said Nyathi in a statement.
Nyathi said the group started to chant party slogans and sing.
"A concerned citizen made an official report to the police.
"The Police reacted and arrested 40 CCC activists who were led by Grandmore Hakata.
"Hakata actually scuffled with the police officers as they effected arrests.
"The Zimbabwe Republic Police has also recovered the three trucks and radio speakers which were being used by the CCC supporters in the unsanctioned car rally."
The arrest comes just a week before the crucial plebiscite.
CCC which is the ruling party's main opponent has been encountering several setbacks during the campaign season, which has seen its members getting arrested, injured, or killed in the build-up to election day.
Posting on her social media platforms, CCC spokesperson Fadzayi Mahere complained that their members got arrested for holding an event but the ruling party, Zanu PF has been conducting the same without any disturbances.