In a speech to the French community during a visit to Washington, Hollande hailed the climate conference as "the most important event of recent years."
The decision to hold the November 30-December 11 climate summit is "our best response to the terrorist attacks" claimed by the Islamic State group," he added.
"No one has asked us to suspend, delay it because in fact it is the most beautiful symbol we can imagine after the tragedy in Paris and Saint-Denis."
Some 140 to 150 heads of state or government are due to attend.
Hollande spoke for about 20 minutes before several hundreds of French people at the French Embassy.
Flowers still lay in front of the embassy in remembrance of the victims of the attacks.
Condemning the assaults as an attack on the French way of life, Hollande urged expatriates to "continue to live."
"Living well, eating well... Our joie de vivre, our human qualities, our way of welcoming others, celebrating, culture -- all of this was hailed by our friends around the world, and we must keep shining in this way."
After his speech, hundreds sang the French national anthem, La Marseillaise.
The French leader was all smiles for a dozen minutes as he shook hands, with many guests thanking him with a warm "merci."
Earlier President Barack Obama told his French counterpart the United States stands united with France against terror.
"We are all French," Obama told Hollande, in French, after hosting him at the White House for talks on how to confront the threat posed by Islamic State.
"We are here to declare that the United States and France stand united in total solidarity to deliver justice to terrorists and those who sent them, and to defend our nations," he said.