Hollande called for "rich countries to help poor countries fight global warming" ahead of the UN Climate Conference set to take place in Paris at the end of this year.
The Caribbean islands contribute only 0.3 per cent of greenhouse gases to the atmosphere but suffer their effects in a rise in sea levels, increasingly extreme weather and the spread of sargassum algae that harm seashores.
"If there is nothing in terms of finance for countries that are the most vulnerable and the poorest, they won't follow you," Hollande told the world's rich nations.
The summit in Martinique's main town, Fort de France, was attended by Haitian President Michel Martelly, 13 prime ministers and six ministers, including Cuba's Environment Minister Elba Rosa Prez Montoya.
Hollande is to make the first-ever visit by French president to Cuba on Monday as relations between the Communist Party-ruled island and the US improve.
The islands have the means to fight climate change, said French Environment minister Ségolène Royal, who joined three other participants to read a "Declaration of Fort de France" that appealed on the world's conscience to fight global warming.
Martinique regional president Serge Letchimy opened the summit with an alarm call, pointing out that "half of the islands in the Bahamas could vanish due to rising sea levels".
Most governments have declared their support for a target of keeping global warming below 2.0°C but the last international summit in Copenhagen six years ago was regarded as a failure.