Militants advanced to within 60 miles of Islamabad, the capital, last month and were pushed back only when the US put pressure on Pakistan to launch a counter-offensive.
Gen Petraeus, the head of Central Command, which covers all US forces in the Middle East and south Asia, is reported to have said that "the Pakistanis have run out of excuses" and now accept that tough action has to be taken to guarantee the government's survival.
Gen Petraeus, who oversaw the American troop surge credited with quelling the insurgency in Iraq, is reported to have wearied of Pakistan's excuses for failing to take on the Taliban.
According to Fox News, he told colleagues "we have heard it all before".
He is reported to have urged concrete action to destroy the Taliban in the next two weeks before determining the United States' next course of action.
Gen Petraeus made the assessment in private talks with congressmen and members of the senate, according to Fox.