Zeid Ra'ad al-Hussein said some comments by the Republican nominee are "deeply unsettling and disturbing," particularly on torture and about "vulnerable people."
According to the Associated Press, Zeid, a Jordanian prince, also told reporters Wednesday he doesn't plan to tone down his recent remarks decrying dangers posed by "populists and demagogues."
Russia's ambassador to the United Nations said Wednesday that Zeid shouldn't criticize foreign heads of state and government.
On the US election, Zeid said: "If Donald Trump is elected, on the basis of what he has said already and unless that changes, I think it's without any doubt that he would be dangerous from an international point of view."