Saudi King Salman bin Abdulaziz will visit the United States later this year, US Secretary of Defence Ashton Carter told reporters following his talks with Saudi monarchs.

US President Barack Obama looks forward to welcoming the Saudi monarch in September, Carter said as he sought to reassure Washington's allies in the region.

Carter was on a Middle East tour that took him to Israel and Jordan earlier in order to lobby for the Iran nuclear deal, besides refurbishing ties with Iran's rivals in the region.

Along with the Saudi king, the recently-nominated defence minister and deputy crown prince Mohammad bin Salman was also present during the talks with Carter.

"Both the king and the minister reiterated their support of the Iranian nuclear deal. The only reservations we discussed were ones that we thoroughly share, mainly that we attend to verification of the agreement as it is implemented," Carter told accompanying reporters on his plane, according to the AFP.

The Sunni-dominated kingdom, a powerful regional rival of Iran, fears the Shiite-inclined Tehran could race up to make nuclear weapons, violating the agreement it signed with world powers.

Conflict-hit Yemen, where Saudi forces are pounding the Iran-backed Shiite Houthi rebels, also featured in the talks between the American official and the Saudi monarch.

"We talked about the need that both the Saudis and we share for a political settlement in Yemen. That is the way to peace, to restore the humanitarian situation there," said Carter.

Riyadh has been accusing Iran of strongly influencing the conflict zones in Iraq, Syria and Yemen.