Pakistani troops have killed at least 15 militants in fighting near the Afghan border, officials say.
Thousands of troops are in Waziristan
The army used helicopter gunships against the militants after a rocket attack on an army post killed a soldier in the North Waziristan region.
On Thursday, Pakistani President Pervez Musharraf warned foreign militants suspected of operating in North Waziristan to leave the country.
More than 150 people have been killed in the region this month.
The latest fighting took place near the main town in North Waziristan, Miranshah.
"They attacked a check post with rocket fire and when we responded the miscreants withdrew into the darkness," military spokesman Major General Shaukat Sultan told Reuters news agency.
Witnesses say gunship helicopters were also used.
The spokesman said soldiers had recovered weapons and ammunition from the militants who managed to escape.
Several of the militants are thought to be foreigners.
On Thursday, President Musharraf warned foreign militants alleged to be fighting in the area to leave or be "crushed".
Earlier this month, three days of heavy clashes with security forces in North Waziristan left more than 120 militants dead, the army said.
Thousands of Pakistani soldiers have been deployed in the volatile tribal region along the Afghan border to flush out Taleban and al-Qaeda militants believed to be hiding in the area.
Observers say North Waziristan is among the last bases for the resurgent Taleban in their battle against the Afghan government.