Chris Bowen says people should not use electricity for two hours every evening if they "have a choice".
However, he added he was "confident" that blackouts could be avoided.
It comes after Australia's main wholesale electricity market was suspended because of a surge in prices.
Mr Bowen asked people living in New South Wales to conserve as much power as possible.
"If you have a choice about when to run certain items, don't run them from 6 to 8 [in the evening]," he said during a televised media conference in Canberra.
