Amnesty International said Washington was using the so-called war on terror to justify the use of lethal force against suspected terrorists.
Authorities at the United Nations in October said there were troubling trends emerging in counter-terrorism operations, where some conflicts know no borders.
U.S.-Pakistani relations soured in May 2011 when a team of U.S. Navy SEALs stormed a compound in Pakistan and killed al-Qaida leader Osama bin Laden. That raid raised legal questions as the countries aren't at war with each other.
In Yemen, a suspected CIA drone killed U.S.-born al-Qaida ideologue Anwar al-Awlaki last year as he traveled in a region of the country known to be sympathetic to al-Qaida.
Amnesty International said the justification weakens the credibility of the United States when it comes to pressing for human rights in other countries.
"There has also been widespread speculation that current U.S. policies and practices with respect to such killings may inadvertently be building support for the very armed groups and terror attacks that U.S. officials say provide its justification," Amnesty International said.
Washington uses policies enacted after the Sept. 11, 2001, attacks by al-Qaida to justify its policies against suspected terrorists.