Zanu-PF's highest decision-making body, the politburo, also met and endorsed the formation of a new government, Chinamasa added.
An agreement reached late on Thursday after four days of tough negotiations followed a ruinous political stalemate between the 84-year-old Mugabe and Tsvangirai.
Both the police and the military have been blamed for state-orchestrated violence and torture of Mugabe's opponents.
The deal, brokered by Thabo Mbeki, South Africa's president, is expected to be signed in the capital, Harare, on Monday in the presence of a number of African heads of state.
There is widespread international interest in the details of the deal which will be officially released at the ceremony.
One sources told the AFP news agency on Friday that Mugabe would be president and head of state, while Tsvangirai would be prime minister and head of the goverment with two deputies.
Mugabe will chair the cabinet and Tsvangirai will chair a council of ministers.
Under the agreement, Tsvangirai would also preside over a national security council- commonly known as the joint operations command - which includes both the army and police.
"Power will be shared, no one will get more power than the other party, even [in] the hiring and firing of cabinet members," the source explained.
"All decisions are made by the council, but the council will have to report back to Mugabe."
The agreement hopefully would end a bloody political stalemate triggered by Mugabe's controversial re-election. Though Tsvangirai won the first round presidential vote, he failed to win an outright victory, prompting a run-off.
He then boycotted the run-off, alleging government intimidation. Mugabe won a landslide, but the victory lacked legitimacy and pushed the country deeper into a festering crisis.