He added: "Haiti needs the massive support of its partners in the international community in the medium and long term. The extent of the task requires that we do more, that we do better and, without a doubt, that we work differently."
Canadian Foreign Minister Lawrence Cannon welcomed the US offer to host an international donors' conference in March.
"We now have the beginnings of a road map toward Haiti's long-term reconstruction and a clear and sustained commitment to follow through," Mr Cannon was quoted as saying by French news agency AFP.
Mr Cannon said one goal was to "physically get the Haitian government back on its feet".
The quake destroyed key government buildings, including the National Palace.
UK-based charity Oxfam has urged the international community to get Haiti's foreign debts cancelled.
It said about $900m (£557m) owed to donor countries and institutions should be written off.
Many operations are still taking place in makeshift outdoor theatres
The World Bank has already announced that it is waiving Haiti's debt payments for the next five years.
And the Paris Club of creditor governments - including the US, UK, France and Germany - has called on other nations to follow its lead in cancelling debts to Haiti. Venezuela and Taiwan are the other biggest creditors.
Although aid continues to flow into Haiti, the head of Italy's civil protection service has strongly criticised the relief effort and the role of thousands of US troops sent there.
Guido Bertolaso described the international aid operation as "a terrible situation that could have been managed much better".
"When there is an emergency, it triggers a vanity parade. Lots of people go there anxious to show that their country is big and important, showing solidarity," he said on Sunday.
Mr Bertolaso, an Italian government minister, said it was "commendable" for the US to lead relief efforts, but "too many officers" meant they had not been able to find a capable leader.
Christian Fraser describes the situation at Haiti's heavily-damaged port
Aid workers have also criticised Haitian government plans to relocate hundreds of thousands of people from the capital, Port-au-Prince, to large camps outside the city.
Caroline Gluck, from Oxfam, told the BBC the move could be dangerous for the survivors.
"In the past, experience has told us establishing some huge camps can cause all kinds of security problems, for example, robberies, rapes and kind of gang activities if the camps are kept too big," she said.
Oxfam was pressing for the camps to be smaller, she added.
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