Riyadh, US President Barack Obama on Thursday pledged to remain vigilant against Iran's destabilizing activities in the Middle East as he tried to comfort his Gulf allies. "None of our nations have an interest in conflict with Iran," Obama said in a brief press conference after meeting with leaders of the Gulf Cooperation Council (GCC) countries in the Saudi capital Riyadh. The GCC comprises Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates. The Persian Gulf nations, Saudi Arabia in particular, have repeatedly raised concerns that the nuclear deal reached with Iran last year will further empower the Islamic Republic to interfere in Arab affairs. The tensions reached a new high in January when Riyadh and a number of its Sunni Arab allies cut diplomatic ties with Tehran, after mobs ransacked the Saudi embassy in response to the execution of a prominent Shiite cleric in Saudi Arabia. "When we entered into negotiations with Iran on the nuclear deal there was concern that in the interest of getting a deal done we would somehow look the other way with respect to other destabilizing activities," Obama said. The US president said the deal has "cut off every single one of Iran's pathways to a nuclear weapon," but the United States continues to have "serious concerns" about Iran's behaviour in the region. During the US-GCC summit, leaders also committed to urgently undertake additional steps to intensify the campaign to defeat the Islamic State (IS) militant group and the Al-Qaeda, and reduce regional and sectarian tensions that fuel instability, said a White House statement. It's Obama's fourth visit to the oil-rich Gulf nation since taking office in 2009. The kingdom was seen as one of Washington's most strategic allies in the Middle East, but bilateral relations have been strained by the nuclear deal reached with Iran last year. A day earlier, President Obama met with King Salman bin Abdulaziz at Erga Palace. Obama underscored the importance of accelerating the campaign against the IS group and welcomed Saudi Arabia's important role in the coalition against the terrorist group, read a White House statement. The two leaders also discussed regional conflicts in Syria, Yemen and Iraq, and challenges posed by Iran's provocative activities. Almost a year ago, in May 2015, Obama hosted leaders of Gulf nations at the White House and the Camp David retreat, the first meeting of the Gulf countries after a framework agreement on limiting Iran's nuclear program. Except for Kuwait and Qatar, top leaders from four of the six-member GCC countries were absent from the 2015 Summit.