BEIRUT, Lebanon — Despite attacks that have killed dozens of civilians at a time, the Trump administration on Wednesday certified that Saudi Arabia and the United Arab Emirates are doing enough to minimize the deadly impact of their military campaign in Yemen.

The certification, announced by Secretary of State Mike Pompeo, was legally required to allow American military aircraft to continue refueling warplanes belonging to the two Gulf nations, the dominant members of an Arab coalition fighting a brutal war in Yemen that has helped create the world’s worst humanitarian crisis.

Mr. Pompeo’s move came amid rising concern in Washington about the coalition’s prosecution of the war and worries among some lawmakers that American weapons were being used to commit war crimes and that American officials could be held liable.

In its efforts to oust Yemen’s Houthi rebels from the capital, Sana, the coalition has bombed weddings, funerals, factories and other civilian infrastructure, often with munitions acquired from the United States. The aerial assaults have elicited harsh criticisms from United Nations investigators and human rights groups, who have also accused the Houthis of violating the laws of war.