The fighting erupted in the Wacha Mela area 65 kilometres (40 miles) west of Miranshah, the capital of North Waziristan tribal district.
Almost 100 militants have been killed since supporters of commander Khalid Mehsud, alias Khan Said Sajna, and the followers of the slain former Taliban chief Hakimullah Mehsud began fighting in April.
Khalid Mehsud's group last week split from the umbrella Tehreek-e-Taliban Pakistan (TTP), a move analysts described as a victory for the Pakistani military's strategy of sowing divisions among insurgent factions.
"The fresh clashes left seven militants dead, five of them belonging to Hakimullah group," a local intelligence official told AFP.
He said at least three rebels were wounded in the clashes.
A militant source also confirmed the clashes and fatalities.
Prime Minister Nawaz Sharif's government began negotiations with the TTP through intermediaries in February, with a ceasefire beginning March 1 but breaking down a month later.
North Waziristan is one of the seven rugged semi-autonomous tribal areas along the Afghan border, an area long tagged by Washington as the most dangerous place in the world.
Pakistan has been battling a homegrown Islamist insurgency that has claimed thousands of lives for the past decade.