Defeated Kenyan presidential candidate Raila Odinga has said he will seek peaceful ways to end a row over poll results, which gave a narrow first round victory to rival Uhuru Kenyatta.
He was speaking after Kenya's Supreme Court upheld Mr Kenyatta's victory, rejecting Mr Odinga's challenges.
He said he accepted the court verdict because he wanted to avoid bloodshed.
But two people died and 11 were hurt as Odinga supporters clashed with police in his western stronghold of Kisumu.
There was an angry mood in the Nairobi slums of Kibera, says the BBC's Gabriel Gatehouse in the city, and police briefly used tear gas to chase away protesters outside the courthouse. Tensions were reported in another slum, Mathare.
But our correspondent says that dire predictions of a return to the violence of five years ago has not yet come true, and any lingering questions over the conduct of the election have been subordinated to an overwhelming national imperative: peace.
The violence that followed a disputed election in 2007 left more than 1,200 people dead.
The presidential, legislative and municipal elections held on 4 March were the first since the 2007 poll.
Official results said Mr Kenyatta beat Mr Odinga - who is currently prime minister - by 50.07% to 43.28%, avoiding a run-off by just 8,100 votes.
Mr Kenyatta and his running mate, William Ruto, are expected to be sworn in as president and vice-president on 9 April.
But they are facing trial on charges of crimes against humanity at the International Criminal Court (ICC) for allegedly fuelling unrest after that election. They deny the charges.
In a BBC interview, Mr Odinga said he wanted to avoid the kind of bloodshed that had occurred five years ago.
"I am going to tell my people to look at peaceful ways of resolving this issue," he said. "The Supreme Court is just one step, there are many other avenues.
"Wounds have not been healed, in fact they've been opened up by what's happened."
He hinted that if nothing was done there could be a return to violence.
"I fear that five years from now, there will be voter apathy. This will lead people to explore other means to resolve this issue," he said.
Some of Mr Odinga's supporters were less diplomatic.
"We cannot trust the court, democracy is dead in Kenya," one man protesting outside the courthouse told the BBC.
Earlier the court, in a unanimous decision, declared the elections free and fair and said Mr Kenyatta had been "validly elected".
Supporters of Mr Kenyatta took to the streets of central Nairobi after the verdict, tooting their horns, blowing on vuvuzelas and chanting.
The president-elect made a televised victory speech hours after the announcement, vowing to work with and serve all Kenyans "without any discrimination whatsoever".
Mr Odinga responded to the verdict with a speech expressing "dismay" at the conduct of the election but saying he fully respected the court's decision.
Petitions had been filed to the court by the prime minister and by civil society groups, who claimed irregularities had affected the election result and called for fresh elections. However, much of their evidence was dismissed by the court.
The Independent Electoral and Boundaries Commission (IEBC) has insisted that the vote was credible, despite technical failures with an electronic voter ID system and the vote counting mechanism.
International observers said the poll was largely free, fair and credible, and that the electoral commission had conducted its business in an open and transparent manner.