US Secretary of State Condoleezza Rice has urged Kenya's rival leaders to put aside their personal agendas and share power to end the political crisis.
Ms Rice is the highest-ranking US official to visit since the election
She dismissed suggestions from Kenyan ministers that the US was meddling in Kenyan affairs.
"This is not a matter of dictating a solution to Kenyans," she said after meeting President Mwai Kibaki and opposition leader Raila Odinga.
At least 1,000 people have died in the clashes over claims of poll-rigging.
The two sides are due to resume talks on a possible power-sharing deal on Tuesday, mediated by former UN Secretary General Kofi Annan.
Ms Rice said a coalition was needed "so that Kenya can be governed".
The BBC's Karen Allen in Nairobi says Ms Rice's visit was never expected to end in a deal - but it has underscored the sense of growing impatience that the political deadlock in Kenya still persists two months after disputed elections.
Ms Rice arrived in Nairobi and went straight into a meeting with Mr Annan, who briefed her on the discussions so far.
Mr Kibaki's team insists he was rightfully elected and has been reluctant to share power.
However it has said it would be ready to change the constitution, which could pave the way for Mr Odinga to get the new post of prime minister.
"It can't be that there is simply the illusion of power-sharing, it has to be real," Ms Rice cautioned.
Our correspondent says two weeks of negotiations have made little headway on the controversial issue of power-sharing.
She says that although both sides have agreed the idea of a grand coalition in principle, they appear deadlocked over how it should work in practice.
Ms Rice also dismissed the foreign minister's warning to the international community not to use threats to make the two sides reach a deal.
"It's Kenyans who are insisting that their political leaders, that their political class finds a solution to the crisis so that Kenya can move forward," she said.
Ms Rice said the 27 December presidential election had not produced "an outcome that can lead to the governance of Kenya".
Mr Annan said there had been no attempt by the international community to impose a solution, but simply an insistence that a solution should be found.
Kofi Annan has said the two rivals are very close to a deal
On Friday, the former Un secretary general announced that both sides had agreed to set up an independent panel, including Kenyan and non-Kenyan experts, to investigate "all aspects" of the disputed election.
The committee is due to start work on 15 March and submit its report within three to six months, he added.
"We are there, we are very close, we are moving steadily," Mr Annan said after two days of closed-door talks to end the crisis.
Foreign diplomats have warned representatives of both sides of dire consequences if they scupper the process.