Kerry said after meeting fellow foreign ministers from the six energy-exporting countries of the Gulf Cooperation Council in Qatar that he and they agreed that once fully implemented, the accord would contribute to the region's security.
But, in apparent acknowledgement of Gulf Arab fears that the regional balance of power may be tilting towards Tehran, Kerry said the discussions also covered "our cooperation in countering the destabilizing activities taking place in the region".
Most Gulf Arab states worry that Iran's July 14 accord with the United States and other big powers will usher in detente between Tehran and Washington and embolden the Islamic Republic to support paramilitary allies in the region.
Last month, six world powers agreed to lift sanctions on Iran in return for curbs on its uranium enrichment program, which the West suspects was aimed at developing an atomic bomb but which Tehran says is for peaceful energy only.
Kerry told a news conference in the Qatari capital Doha: "Today my counterparts and I discussed the steps that we will take and how we intend to build an even stronger, more enduring and more strategic partnership with particular focus on our cooperative counter-terrorism, counter-insurgency."
He said the ministers also discussed missile defense and expediting arms transfers. Additional US cooperation with Gulf states would include intelligence-sharing and special forces training.