In its first report on Washington's rights record since 2006, it also called for the prosecution of anyone who ordered or carried out killings, abductions and torture under a CIA program at the time of President George W. Bush, and to keep an obligation to close the detention facility at Guantanamo Bay.
U.S. officials did not immediately comment on the findings of the U.N. Human Rights Committee, which is made up of 18 independent experts.
The Obama administration increased the number of drone strikes after taking office in 2009. It has been under pressure from affected governments, the United Nations and activists to rein in the strikes and do more to protect civilians who are mainly targeted in the strikes.
The United States should give more information on how it decided someone was enough of an "imminent threat" to be targeted in covert operations in Pakistan, Afghanistan, Yemen and Somalia and other countries, the report said.
It should "revisit its position regarding legal justifications for the use of deadly force through drone attacks," investigate any abuses and compensate victims' families, the committee added in its conclusions.
The committee also called for more investigations into intelligence operations launched by the administration of President George W. Bush in the wake of the Sept. 11 2001 attacks on America.
Critics say the CIA program used harsh interrogation methods, including "waterboarding" or simulated drowning, that constituted torture banned by international law.
There has only been a limited number of investigations into "unlawful killings ... and the use of torture or cruel, inhuman or degrading treatment or punishment of detainees in U.S. custody, including outside its territory, as part of the so-called 'enhanced interrogation techniques' program," it said.
The report welcomed Obama's order in January 2009 to end the CIA program but it noted with concern that all reported investigations into alleged abuses were closed in 2012 "leading only to a meagre number of criminal charges brought against low-level operatives."
The panel said many details of the CIA program remained secret, hindering accountability and redress for victims.
In an apparent reference to lawyers who drew up memos justifying the Bush-era interrogation techniques, it said: "The responsibility of those who provided legal pretexts for manifestly illegal behavior should also be established.
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