June 29 (Reuters) - Gulf stock markets fell at the open on Monday as investors remained concerned about the exchange of strikes between the United States and Iran in recent days, despite the two countries agreeing to refrain from launching any further attacks.

A new effort has begun to revive diplomacy in the Middle East after days of escalating tensions following Iran's targeting of a cargo ship in the Strait of Hormuz with a projectile last week. The two sides have since traded accusations of violating the temporary ceasefire.

Uncertainty over the durability of the ceasefire agreement led to higher oil prices, although crude has given up most of its war-related gains since the agreement was reached, and markets quickly reassessed the likelihood of easing supply pressures.

The 14-point interim peace agreement, reached on June 17, aimed to halt the fighting, reopen the Strait of Hormuz, and allow for continued negotiations on issues including Iran's nuclear program. The United States and Israel launched their war against Iran on February 28.

Saudi Arabia’s main index fell 0.6 percent, weighed down by a 1.1 percent drop in shares of oil giant Saudi Aramco, one day after breaking an eight-session losing streak.

Aramco resumed crude oil loading operations at the Ras Tanura terminal west of the Strait of Hormuz on Friday, after a nearly four-month hiatus.

Dubai's main index fell 0.2 percent, with shares of Emirates NBD, the UAE's largest bank, dropping 0.8 percent and Air Arabia shares declining 0.9 percent.

The main index in Abu Dhabi fell 0.2 percent.

Qatar's main index lost 0.2 percent, weighed down by a 0.7 percent decline in Qatar Islamic Bank.