The embassy in the UAE capital, Abu Dhabi, and the US consulate in Dubai reopened, as the holiday marking the end of the fasting month came to a close in the southern Gulf state.
The embassy in Libya also reopened on Sunday.
In Saudi Arabia, the Riyadh embassy and the consulates in Jeddah and Dhahran remained closed, as did the US embassy in neighbouring Qatar. They are due to reopen on August 14, when the holidays end in those two nations.
In Bahrain and Kuwait, the American embassies are due to reopen on Monday.
Washington closed of its 19 missions in the Middle East and Africa last week following a security alert.
Communications intercepts reportedly included an attack order from Al Qaeda leader Ayman al-Zawahiri to Yemen-based Al Qaeda in the Arabian Peninsula.
The United States said on Friday that all of the embassies it shut would reopen this week, except the mission in Yemen.