They are helping the three Pacific countries battered by Cyclone Harold last week, Vanuatu, Tonga, and Fiji.
But the executive director of the Council of International Development, Josie Pagani, said that during the lockdown the charities aren't able to fundraise and the public can't donate.
She said the international aid charities typically get about two thirds of their revenue from public donations.
Cyclone Harold, the worst to hit Vanuatu since deadly Cyclone Pam in 2015, has wrecked around 70 percent of the buildings in Luganville, and much of the vegetation.
Ms Pagani said aid organisations won't be allowed to enter the countries due to Covid -19 but she said there is a still a lot they can do and are doing.
She said his includes releasing stock, from tarpaulins for shelter to wash kits for sanitation, and money to support and pay the salaries of their Pacific partners - the first responders, who need all the help they can get.