Mr Bush, reacting to a UN report that confirmed at least 31 people died in a recent crackdown, said there could be no "business as usual" with the junta.
He said the US would lead efforts to place more sanctions on the regime.
Mr Bush, who already imposed tough sanctions against the junta in October, pledged further action after a new UN report shed light on the scale of repression in Burma.
Illicit Burmese trade
The UN's human rights envoy, Paulo Sergio Pinheiro, said at least 31 people had died as the ruling generals sought to regain control after a wave of peaceful protests swept the country in September.
"Mr Pinheiro's report demonstrates why the world cannot go back to business as usual with [Burma's leader] Gen Than Shwe and his junta," Mr Bush said in a statement.
"I call on all members of the international community to condemn the atrocities detailed in Mr Pinheiro's report in the strongest possible terms."
Profile: Aung San Suu Kyi
Like the South African leader Nelson Mandela, Aung San Suu Kyi has become an international symbol of heroic and peaceful resistance in the face of oppression.
For the Burmese people, Aung San Suu Kyi, 62, represents their best and perhaps sole hope that one day there will be an end to the country's military repression.
As a pro-democracy campaigner and leader of the opposition National League for Democracy party ( NLD), she has spent more than 11 of the past 18 years in some form of detention under Burma's military regime.