Liberia's electoral commission has dismissed charges of electoral fraud brought by football star George Weah.
George Weah's supporters say the poll was rigged
An election official said there had been errors but not massive fraud.
Earlier, the African Union urged Mr Weah to accept defeat in the polls, won by economist Ellen Johnson-Sirleaf.
African Union Chairman Alpha Oumar Konare said he was concerned that further protests by Mr Weah's supporters could undermine peace.
US Secretary of State Condoleezza Rice praised Liberia's polls after meeting Mrs Johnson-Sirleaf in Washington on Thursday.
"The statistics provided by the CDC [Mr Weah's party] in their complaint do not constitute massive fraud," said National Electoral Commission's (NEC) presiding officer Joseph Blidi.
"The evidence adduced was grossly insufficient. There were some errors but they were not wilful or intentional acts that would constitute fraud."
Mrs Johnson-Sirleaf won 59% of the vote in November's run-off, against 41% for Mr Weah, who gained most votes in the first round.
Earlier this week, Liberian police clashed with Mr Weah's supporters after he had given a speech, saying Mrs Johnson-Sirleaf would not be sworn in as planned in January. Mrs Johnson-Sirleaf is set to become Liberia's first elected head of state since the end of 14 years of war in 2003.
She will also be Africa's first elected woman president.