RIYADH: US President Barack Obama said on Thursday that Washington and Gulf Arab states were united against the militant Islamic State (IS) group as he sought to overcome strains on Iran to boost efforts against the militants.

In Riyadh for talks hosted by Tehran’s arch-rival Saudi Arabia, Obama said the United States still has “serious concerns” about Iran, but insisted no country has an interest in conflict with the Shia power.

Obama, on likely his final presidential visit to America’s historic Gulf allies, was in Riyadh seeking to reduce tensions with the Arab states rooted in US overtures to their regional rival Tehran.

With the IS suffering a series of recent setbacks in areas under their control in Syria and Iraq, Washington is seeking more help from the oil-rich Gulf monarchies to keep up the pressure.

Speaking at the close of the summit of the six-nation Gulf Cooperation Council (GCC), Obama played down any divisions and vowed continued cooperation in the battle against the extremists. “We remain united in our fight to destroy (IS),” he said.

“Given the ongoing threats in the region, the United States will continue to increase our security cooperation with our GCC partners including helping them improve their own capacity to defend themselves,” Obama said.

Seated beside Saudi King Salman inside a Riyadh royal palace, Obama said concerns remained about Iran’s “destabilising activities” despite its landmark nuclear agreement with world powers and the lifting of sanctions.

“Even with the nuclear deal we recognise collectively that we continue to have serious concerns about Iranian behaviour,” Obama said. He warned, however, of the risk of confrontation with Tehran.

“None of our nations have an interest in conflict with Iran,” Obama said.

Iran’s emergence from international isolation following the nuclear deal has worried the Gulf monarchies, who fear Tehran will be emboldened to seek a still bigger regional role.