He lauded the leader of the opposition, Raila Odinga, for embarking a peaceful electoral campaign, which showed that he was a courageous defender of democracy.
The opposition last week said going to court was not an option, but Odinga on Wednesday made it clear they had changed their minds.
Police and the government have disputed the death toll, putting the count at 10.
He has not publicly provided evidence to support his claim or clarified where he obtained alternative tallies showing him leading by several hundred thousand votes.
"How the case is handled by the courts will be very important", said Emma Gordon, an analyst at Bath, England-based risk adviser Verisk Maplecroft.
The U.S. Press Secretary in a statement issued by embassy in Nairobi Tuesday also welcomed the statements by global and domestic observer missions affirming the credibility of the election.
But while there have been scattered protests in Odinga strongholds, the demonstrations were relatively muted as supporters waited to hear what Odinga had to say.
He has rejected the results, which gave Kenyatta, 55, a second term with 54 per cent of the vote.
Kenya is the wealthiest country in East Africa, and has emerged as a pillar of stability in a fragile region, which includes war-torn neighbors Somalia and South Sudan. Kenya is always much larger than my individual ambition.
That rift predates the country's independence in 1963, and some worry that Odinga's refusal to concede will further complicate reconciliation efforts. "We see these documents flying in the media and never directed to us", said Kegoro.
The men said they were anxious by Odinga's allegations but said they could not afford the consequences of violence in their city, which saw some of the worst clashes a decade ago.
Civil society activists say Kenya Revenue Authority officials and police have raided the offices of a group that found anomalies in the recent elections in which President Uhuru Kenyatta was re-elected. The Kenyan National Human Rights Commission accused security forces of using "excessive force which is unlawful and unacceptable" against demonstrators.
According to Reuters, acting Interior Minister Fred Matiang'i instructed Fazul Mohamed, head of the non-government organization coordination board, to suspend action against the organizations for up to 90 days while talks with the government are held.
NASA presidential candidate Raila Odinga with his running mate Kalonzo Musyoka during their rally in Kibera, Nairobi, on July 18, 2017. Packed minibuses streaked through the slum's main arteries.
Life is returning to normal and residents of the capital are "safe and secure", said Nairobi police chief Japheth Koome.
His challenge after losing the 2013 election was unsuccessful.
USA And Universal Health Care
This is because the each state has its own different set-up on all levels socially, financially and geographically. Each state has populations equivalent to nations with universal coverage hence size can never be a limiting issue.