Protesters gathered as the president of Myanmar arrived at the White House.
Rights groups and some US lawmakers think Obama has moved too quickly since a breakthrough in relations in 2011.
Thein Sein is the first leader of the country, also known as Burma, to make an official visit to the US in 47 years.
He admitted to President Obama that democracy reforms were a daunting challenge. Citing poverty and a lack of job opportunities, Sein agreed his people must become more familiar with democratic norms and values.
Obama agreed but insisted violence against Muslim communities must stop:“The displacement of people, the violence directed towards them needs to stop and we are prepared to work in any ways that we can with both the government of Myanmar and the international community to assure that people are getting the help that they need, but more importantly, that their rights and their dignity is recognized over the long term”.
At least 192 people died in ethnic violence last year mostly in the western state of Rakhine.
Most of the victims, and the 140,000 people made homeless in the attacks, were Muslims.