RIYADH, Saudi Arabia — A Saudi-led coalition in Yemen acknowledged Saturday that an air attack last month that killed dozens of people, including children traveling on a bus, was unjustified, and it pledged to hold accountable anyone who contributed to the error.

The rare concession came after mounting international pressure, including from allies, to do more to limit civilian casualties in a three-and-a-half-year civil war in Yemen that has killed more than 10,000 people and pushed the already impoverished country to the brink of famine.

The Western-backed alliance fighting the Iranian-aligned Houthi rebels in Yemen had said after the Aug. 9 airstrikes, at a market in Saada Province, that it had been targeting missile launchers that were used to attack southern Saudi Arabia a day earlier. The alliance accused the Houthis of using children as human shields.

The Joint Incident Assessment Team, an investigative body set up by the coalition, said on Saturday that the strikes had been based on intelligence indicating that the bus was carrying Houthi leaders, a legitimate military target, but that delays in executing the strike and receiving a no-strike order should be investigated further.