UK Prime Minister Gordon Brown said he was "saddened and angry" by the verdict and described the trial as a "sham".
In a strongly-worded statement, Mr Brown said it was "a purely political sentence".
A statement from the office of Nicolas Sarkozy said the French president was calling on the European Union to impose new sanctions on Burma.
The EU presidency said it would impose "additional targeted measures against those responsible for the verdict".
US Secretary of State Hillary Clinton said Aung San Suu Kyi should not have been convicted, and she also called for the release of American citizen John Yettaw. We are concerned about the harsh sentence imposed on him, especially in light of his medical condition," she told reporters.
Mr Yettaw is believed to have epilepsy, diabetes and post-traumatic stress disorder, and has been treated at a Rangoon hospital.
Myint Myint Aye, of Ms Suu Kyi's National League for Democracy (NLD) party - the country's main opposition, said the party did not accept the verdict, adding: "We demand her immediate unconditional release and we will keep on pressing."
