In Iran’s case, pushing on human rights is an easy decision, since the Trump administration sees little cost. Iran has emerged as one of the top two or three foreign adversaries of the new president, and he is not seeking economic or security ties with Tehran that could be jeopardized.

In Saudi Arabia, on the other hand, Mr. Trump sees an economic partner and the anchor of a Sunni Arab alliance to counter Iranian influence in the region. He announced $110 billion in arms sales to Saudi Arabia on Saturday, as well as billions of dollars’ worth of business deals.

But the Saudi human rights record is no better than Iran’s. By some measures, it is worse. Iran just completed an election for president, albeit a flawed one, for an office subordinate to the theocratic supreme leader. Saudi Arabia is ruled by an absolute monarchy that does not meaningfully share power or even allow women to drive.

The latest human rights report produced by Mr. Tillerson’s own department mentions Saudi Arabia’s “restrictions on universal rights, such as freedom of expression, including on the internet, and the freedoms of assembly, association, movement and religion,” as well as the country’s “pervasive gender discrimination.” Raif Badawi, a writer, has been in prison since 2012 after starting a blog called Free Saudi Liberals Network.

Freedom House, an advocacy group based in Washington, ranks Saudi Arabia among the 11 least free nations in the world, giving the country a score of 10 out of 100 on its freedom index, below Iran’s 17. Some of the other countries whose leaders met with Mr. Trump on Sunday also have less-than-sterling human rights records, including Bahrain, Kuwait and Qatar.

Michael J. Abramowitz, the president of Freedom House, said, “We are very glad that Secretary Tillerson called out Iran for its egregious failures to respect free speech and free association.”

He added: “We should be holding all countries in the region to account for such violations, including his hosts. Both Saudi Arabia and Iran are among the world’s most oppressive regimes when it comes to fundamental freedoms.”