"I join the international community in calling for Aung San Suu Kyi's immediate, unconditional release," Obama said.
"Today's unjust decision reminds us of the thousands of other political prisoners in Burma who, like Aung San Suu Kyi, have been denied their liberty because of their pursuit of a government that respects the will, rights, and aspirations of all Burmese citizens," Obama said.
Ban Ki-moon, the UN secretary-general, "strongly deplored" Aung San Suu Kyi's sentence and said "unless she and all other political prisoners in Myanmar are released and [are] allowed to participate in free and fair elections, the credibility of the political process will remain in doubt".
UN statement delayed
But a UN statement on the 64-year-old's continued detention failed to materialise on Tuesday as members of the UN Security Council could not agree on the wording of the US-written draft.
"There was considerable support for the principle of a statement, but a number of delegations wanted to refer the statement back to their capitals overnight for advice and instructions," John Sawers, the British ambassador to the UN, said after the closed-door meeting.
Diplomats said delegates from China, Russia, Vietnam and Russia wanted to consult their governments first.
China, which has a veto in the council, has consistently opposed measures such as sanctions against Myanmar.
The US-drafted statement "condemns the conviction and sentencing of Daw Aung San Suu Kyi and expresses grave concern about the political impact this action has on the situation in Myanmar".
The 16-line draft calls for the release of the opposition leader and other political prisoners and demands the government "establish the conditions and create an atmosphere conducive to an inclusive and credible political and electoral process with full participation of all political actors".
Announcing its verdict on Tuesday, the court in the former capital Yangon initially sentenced Aung San Suu Kyi to three years in prison, but that was immediately halved on the orders of the military government which said she could serve the time in her Yangon home.
The Nobel peace laureate had been charged with breaching the terms of her house arrest following an incident in May in which Yettaw swam across a lake to reach her villa.
He was sentenced to seven years' hard labour on Tuesday after the court found him guilty of three charges, including immigration offences and "swimming in a non-swimming area".
| Rallies were held in Thailand, Japan, Britain, South Korea, France and the Philippines [AFP]
Lawyers for Aung San Suu Kyi and Yettaw said on Wednesday that they would appeal the sentences that have sparked outrage in many parts of the world.
Protesters across Asia and in some European capitals held demonstrations on Tuesday, calling for the immediate release of Aung San Suu Kyi.
Rallies were held in Thailand, Japan, South Korea and the Philippines, before the Myanmar court ruled Aung San Suu Kyi was guilty of violating terms of her detention.
Following the verdict, activists gathered outside the Myanmar embassy in London to demand her release.
Anna Roberts, the director of the Burma Campaign UK, which is calling for a global arms embargo on Myanmar, said the "international community has a responsibility".
"Time and again it has failed to act, but now is the time," she said.
London-based Amnesty International also called the sentence "shameful ... nothing more than legal and political theatre".