"We reject this," Rajapakse said. "This resolution only hurts our reconciliation efforts.
It does not help.
"But I am not discouraged. We will continue with the reconciliation process I have started," he added in a phone call.
In a 23-12 vote, the council backed a Western-sponsored resolution which said it was time for a "comprehensive investigation into alleged serious violations and abuses of human rights and related crimes by both parties in Sri Lanka".
Thursday's resolution is the most serious censure demanding an international investigation into allegations that thousands of civilians were killed in the final months of Sri Lanka's Tamil separatist war in 2009.
Rights groups have said that up to 40,000 ethnic Tamil civilians were killed by Sri Lankan forces while defeating separatist rebels, a charge Colombo has denied.
Despite the overall vote, Rajapakse said he had drawn comfort from India's abstention in Geneva which followed widespread expectations that New Delhi would su