Sirisena's office said on Sunday he had sent a "special message" to president-elect Trump seeking US intervention at the council, where Sri Lanka
faces censure for wartime atrocities.
"I sent a special message to Donald Trump
asking him to support us at the (council)," the President said. "I am asking him to help completely clear my country (of war crimes
allegations) and allow us to start afresh."
Sirisena said he was making a similar appeal to the incoming UN Secretary-General Antonio Guterres.
However, during a visit by outgoing Secretary-General Ban Ki-moon
to Sri Lanka
last month, Sirisena had asked for more time to investigate war crimes, a sensitive political issue in the majority-Sinhalese country.
has said it will set up special courts to address issues of accountability, but the promised judicial mechanisms have yet to be established.
There have been allegations that troops killed up to 40,000 minority Tamils
during the final battle against separatist Tamil Tiger rebels in 2009, a period when Sirisena's predecessor and strongman leader Mahinda Rajapakse was in power.
Sirisena said he had been able to "tone down" a US-initiated censure resolution soon after defeating Rajapakse and coming to power in January 2015. But he was keen to secure Trump's help to have the allegations against Sri Lanka
The rights council has asked Sri Lanka
to ensure credible investigations into war crimes, pay reparations to victims and their families and ensure reconciliation after 37 years of ethnic war which claimed at least 100,000 lives.
Troops still have a large presence in the former conflict zones in the north and east and keep a close watch on the local Tamil population, seven years after the end of the war.