He arrived in Phnom Penh late yesterday, after a brief but historic trip to Burma.
During his visit, the first by a sitting American head of state, President Obama praised Burma's leaders for taking steps towards democracy.
But he also warned that more human rights reforms are needed for he country to reach its full potential.
Correspondent: John Stewart
Speaker: Aung San Suu Kyi, Burmese opposition leader; Barack Obama, US President
JOHN STEWART, REPORTER: President Obama arrived with his secretary of state Hillary Clinton on a brief but historic visit to a country once shunned by the international community.
After meeting Burma's prime minister Thein Sein, the president met with Nobel Laureate Aung San Suu Kyi and expressed his admiration for her struggle.
BARACK OBAMA, US PRESIDENT: Here, through so many difficult years, is where she displayed such unbreakable courage and determination.
JOHN STEWART: The president delivered his speech at Rangoon University, a place where teachers and students had formed the heart of Burma's pro-democracy protests over the past two decades.
BARACK OBAMA: Instead of being outlawed, political parties have been allowed to participate. You can see progress being made. As one voter said during the parliamentary elections here, "Our parents and grandparents waited for this, but never saw it." And now you can see it. You can taste freedom.
JOHN STEWART: President Obama urged the Burmese people to put aside religious and ethnic divisions and build a tolerant society without prejudice against minority groups like the Rohingyas.
BARACK OBAMA: I stand before you today as president of the most powerful nation on Earth, but recognising that once, the colour of my skin would have denied me the right to vote. And so that should give you some sense that if our country can transcend its differences, then yours can too.
JOHN STEWART: The president offered closer economic ties with Burma, if the government continues to release political prisoners, improve freedom of the press and reduce corruption.
BARACK OBAMA: The flickers of progress that we have seen must not be extinguished, they must be strengthened, they must become a shining north star for all this nation's people.
JOHN STEWART: Aung San Suu Kyi expressed her gratitude to the president, but urged caution and said that Burma's path to democracy may still have obstacles to overcome.
AUNG SAN SUU KYI, BURMESE OPPOSITION LEADER: The most difficult time in any transition is when we think that success is in sight. Then we have to be very careful that we are not lured by a mirage of success and that we are working towards genuine success for our people and for the friendship between our two countries.
JOHN STEWART: President Obama's speech is being seen by many as an attempt to expand America's influence in South-East Asia and challenge China's presence in the region.