Addressing a joint press conference with Pakistan Prime Minister's adviser on Foreign Affairs Sartaj Aziz, Kerry said the terror groups like the "Pakistani and Afghan Taliban, the Haqqani network, Lashkar-e-Taiba and other groups continue to pose a threat to Pakistan, to its neighbours and to the US."
Kerry, who travelled to Pakistan from India, said all militant groups should be targeted to bring security to the region.
The Haqqani network is blamed for a bloody bombing of the Indian embassy in 2008 that left 58 people dead, a 2011 attack on the US embassy, and several big truck bombing attempts.
US and Afghan officials have repeatedly said Pakistan's spy agency ISI covertly backed the Haqqanis to extend its influence in Afghanistan, a charge Islamabad deny.
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LeT has carried out several attacks in India, including the co-ordinated terror attacks in Mumbai in November 2008 that left 166 people dead, including six Americans.
He said the tragedy was felt in every US household and the US stands with the victims families in their sorrow.
Pakistan launched a massive military operation 'Zarb-e- Azb' in the North Waziristan region in June to flush out militants from the area. More than 1500 militants have been killed in the operation in the region which had become a hub for militant groups who carried out attacks in both Pakistan and Afghanistan and against the US interests in the region.
On his part, Aziz reassured Kerry that "action will be taken without discrimination against all groups".
"Their (Haqqani network) ability to operate from here across to Afghanistan has virtually disappeared," he said.
"We expect our defence forces to remain engaged in counterterrorism operations for some time in the foreseeable future," Aziz said, as he sought aid from the US to help rebuild the regions where army has been fighting militants.