Francois Hollande gave the assurance in a television interview for broadcast on the nine French overseas networks after both La Reunion and New Caledonia were badly hit by strong winds and heavy rain.
The remnants of Cyclone Freda struck New Caledonia, with one person drowning and another still missing.
The overseas territories minister, Victorin Lurel, says he will personally see to the mobilisation of the necessary means.
The minister was in Wallis and Futuna last month after Cyclone Evan destroyed 300 homes amid winds said to have been the strongest since 1968.
Source: The Pacific Island Report