One US serviceman died and four others were wounded in the attack on Sunday, the first major US military action since Donald Trump became president.
The US military's Central Command said it was "likely" that civilians died in the raid, which targeted members of Al-Qaeda in the Arabian Peninsula in the Yakla region of Yemen's Baida province.
"When you think of the loss of life throughout America and institutions and in terms of the world, in terms of what some of the individuals could have done, I think it is a successful operation by all standards," White House spokesman Sean Spicer said, referring to the people targeted in the attack.
He added that it was hard to talk of success when an American soldier was killed, and praised the soldier's sacrifice in fighting what Spicer called people who posed a threat to America.
Signup to our newsletter and follow us on Facebook and Twitter!
Spicer made no mention of civilian victims.
Trump has vowed to fight Islamic extremism relentlessly.
He traveled to an air base in Delaware Wednesday to receive the body of the US Navy SEAL killed in Yemen, identified as Chief Petty Officer William "Ryan" Owens, age 36.
After the raid a Yemeni official said the attack left 41 Al-Qaeda members dead, plus eight women and eight children.
The International Crisis Group, an independent group that analyzes conflicts around the world, said the raid had left many civilians dead including at least 10 women and children.
Human Rights Watch said the United States should compensate the families of those "wrongfully" killed or wounded in the raid.