The resolution, approved by a 25-13 vote with eight countries abstaining, relates to alleged human rights violation against Tamils during the during the final phase of the war in May 2009 between the Sri Lankan army and Tamil rebels that ended the brutal 25-year-old civil war on the island nation for a separate homeland for the Tamil minority.
The resolution encourages the government of Sri Lanka to implement the recommendations made in the report of the Office of the High Commissioner "and also calls upon the government to conduct an independent and credible investigation into allegations of violations of international human rights law and international humanitarian law as applicable," the U.N. agency, in Geneva, Switzerland, said.
The resolution was milder than earlier versions, the BBC reported.
The Sri Lankan representative at the proceedings warned the resolution would work against the reconciliation process in progress.
Amnesty International was quoted as saying the resolution had highlighted rights violations but failed to set up an independent and international investigation into the conflict.
U.S. Secretary of State John Kerry said the vote encourages Sri Lanka to continue on the path toward lasting peace and prosperity following the civil war and instability.
"This resolution, which builds on a similar 2012 resolution, reaffirmed that Sri Lanka must take meaningful action on reconciliation and accountability in order to move forward. The United States, together with international partners, calls upon the government of Sri Lanka to fulfill its public commitments to its own people on these longstanding issues."
Kerry said while some important progress has been made, there is much work still to be done. He said he looked forward "to continuing our engagement with" Sri Lanka and strengthening friendship with its people.