WASHINGTON — Seeking to mend a frayed relationship with a major American ally in the Middle East, President Obama plans to travel to Saudi Arabia in March for a meeting with King Abdullah, an official with knowledge of the planning said Friday.

Mr. Obama, the official said, will seek to reassure the king of American support after a tense period in which the Saudis and other Persian Gulf allies of the United States have grown increasingly frustrated with American policies toward Iran and Syria.

Saudi officials have deep reservations about the interim nuclear deal that the United States and other major powers struck with Iran. They worry that it could presage a broader shift in American alliances from the Sunni monarchs in the gulf toward the Shiite mullahs in Iran.

Saudi Arabia has also been frustrated by Mr. Obama’s unwillingness to do more to support rebel forces in Syria. The Saudis have funneled weapons and other equipment to the rebels, in part because they view the civil war there as a proxy battle between Sunni Arabs and Shiite Iran, which is an important backer of the Syrian president, Bashar al-Assad.