Caretaker Prime Minister Mir Hazar Khan Khoso decided to impose the ban in all government departments and offices, an official statement said.
Khoso directed authorities to introduce a new dress code for government employees to help them cope with the lack of air conditioning.
The dress code includes white or light coloured shirts and trousers or shalwar-kameez with waist coat.
As a special concession, government employees will be allowed to come to work in "shoes without laces" or "sandals without socks", the statement said.
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The Prime Minister's House has already stopped using air conditioners as part of an austerity and conservation drive.
"The measure reflects the resolve of the government to manage the power crisis by management of demand," the statement said.
Authorities were given seven days to implement the ban.
Khoso expressed hope that provincial governments, private institutions and the people would cooperate with his government for energy conservation.
He appealed to people to adopt energy conservation in their homes and workplaces to minimise power cuts.
There are eight hours of power cuts in Islamabad while many rural areas go without electricity for upto 18 hours a day.