Liberia's electoral authorities have begun an inquiry into fraud claims during last week's presidential polls.
A ban on protest rallies has come into immediate effect. With all votes counted Ellen Johnson-Sirleaf won 59% in the run-off election.
On 41%, Congress for Democratic Change candidate and ex-footballer George Weah, alleges that ballot boxes were fraudulently stuffed with voting slips.
The new president will not be confirmed until the investigation is complete.
The BBC's Jonathan Paye-Leyleh in Monrovia says that the inquiry began and then adjourned for several hours, to enable Mr Weah's team to "consolidate" their different complaints to quicken up the process.
The elections, which are the first since the end of 14 years of civil war, were praised as broadly free and fair by both western and African observers.
"In light of the persistent street protests, which are causing panic among citizens... resulting in intermittent closures of schools and business houses, government can no longer allow this situation to continue," interim leader Gyude Bryant said in an address to the nation.
"Government will not under any circumstances accept a situation where some citizens decide to hold the rest of the country hostage because they do not agree with a particular issue or course of action," he said.
Mr Weah has urged his supporters - who include many former combatants - to remain calm. But a CDC party official warned that if Mrs Johnson-Sirleaf is declared the winner, there will be "resistance".
George Weah's supporters have been marching through Monrovia
The 18 CDC members elected to parliament have already threatened to boycott the legislature "if the massive electoral fraud is not addressed adequately".
The CDC won more seats than any other party.
National Elections Commission (NEC) chairwoman Frances Johnson Morris has warned Mrs Johnson-Sirleaf and her supporters not to start celebrating yet.
She said the results would be confirmed by 23 November after the poll complaints had been investigated.
If Mrs Johnson-Sirleaf's victory is confirmed, she would become the first woman to be elected head of state anywhere in Africa.
She rejects claims of vote-rigging as absurd.
The election was held after the 14-civil war ended two years ago.