The United States is urging Uganda to repeal the new anti-gay law that President Yoweri Museveni signed on Monday.
A statement from the White House said Mr. Museveni "took Uganda a step backward" by signing the law, which it said is an affront and a danger to Ugandan gays and reflects poorly on the country's human rights record.
It predicted the law will undermine public health, including efforts to combat AIDS.
Among other measures, the law imposes harsh new penalties for gay sex, and bans the so-called "promotion" of homosexuality.
Amnesty International denounced the law as "deeply offensive" and said it makes a mockery of rights enshrined in the Ugandan constitution.
President Museveni defended the bill at Monday's signing ceremony, asserting that studies show homosexuality to be a choice, not a genetic trait. He also said groups are trying to recruit young Ugandans into a gay lifestyle.
The president has the backing of conservative Ugandan groups. Last week, the Uganda Muslim Supreme Council praised the president as "courageous" for defying Western pressure over the bill and, in the council's words, putting morality first.
The country's parliament passed the measure in December, with a 14-year sentence for first-time offenders and life in prison for those convicted of what the law terms "aggravated
The original bill called for the death penalty in some cases, but that was dropped as Western nations and rights groups denounced the bill.
U.S. President Barack Obama has said he is "deeply disappointed" with the law and that it will complicate U.S.-Ugandan relations.
Homosexuality is illegal in 37 African nations and a taboo subject across many parts of the continent. Activists say few Africans are able to be openly gay.