At least 570 people are now known have died after the magnitude-7.8 quake.
The cost of rebuilding could be as high as $3bn (£2.1bn), President Rafael Correa said.
Even before the earthquake struck, the World Bank had predicted Ecuador's economy would shrink by as much as 2.0% this year.
Oil-rich Ecuador has suffered because of falling oil prices in recent months.
Left-leaning President Correa said all levels of society would be expected to contribute to rebuilding funds, even if they did not live in the worst-hit Pacific region.
Among the measures he announced in a televised address late on Wednesday:
"Society is built with institutionalised commitment, with organised collective action," Mr Correa said.
"This is how a modern society responds to this kind of disaster and the way each Ecuadorian, within his ability, contributes to the recovery of his own motherland."
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Figures given by officials for the number of people missing ranged from 231 to 1,700, with some 4,000 people injured.
Thousands of people have been left homeless, making them vulnerable to dirty drinking water and disease.
Foreign nationals from the UK, Ireland, Canada, Colombia, Cuba and the Dominican Republic have been confirmed among the dead.
A new 6.2-magnitude quake struck off the Ecuadorean coast early on Wednesday. The quake was centred 70km (44 miles) west of Esmeraldas at a shallow depth of 10km.
"You can't imagine what a fright it was. 'Not again!' I thought," Maria Quinones told Reuters in Pedernales, that was close to the epicentre of Saturday's quake.
The World Food Programme and Oxfam are sending supplies, while the UN said it was preparing a "major airlift".
Some people have been pulled out of the rubble alive but hope is fading that others will be found.
Focus is turning to the survivors. The quake damaged communications, transport links and sanitation, hampering relief efforts.
Unicef has warned that 150,000 children have been affected by the disaster and said landslides were complicating rescue efforts in some areas, and some towns were without electricity.
Ecuador's president has introduced new measures to try to pay for rebuilding after Saturday's earthquake, including a one-off tax on millionaires.