"All the people must leave what they are doing, come to Harare... we just want to see the back of Mugabe immediately. The protests must begin now, we cannot have another hour of Mugabe," said Zimbabwe War Veterans' Association chairman Chris Mutsvangwa.
The group urged people to march to Mugabe's private residence, known as the Blue Roof, to ensure the increasingly isolated leader "leaves office immediately".
Lawmakers from Mugabe's ruling ZANU-PF party are due to take the first steps on Tuesday to force Mugabe from office after he ignored their ultimatum to resign.