A decree by junta chief Colonel Mamady Doumbouya, read on state TV, declared the event an issue of "national and priority interest."
All spending for organizational needs "will be processed as a matter of urgency," it said.
The announcement late Monday came on the eve of a two-day mission by the Confederation of African Football (CAF) to monitor Guinea's progress on hosting the big event.
It also declared that land needed for the tournament will fall into the category of public interest, and any property transactions or work not related to the competition will be banned on these sites.
Hosting Africa's biggest sporting event is a major challenge for the impoverished country, which lacks sporting infrastructure and transport.
Guinea was originally scheduled to stage the competition in 2023, but this was pushed back by two years when the list of organising nations was reshuffled in 2018.
The 2023 event will be hosted by Ivory Coast.
Doumbouya led a coup last September that toppled the country's elected president, Alpha Conde.
The takeover has stirred frictions with the influential West African bloc ECOWAS, which has been pushing for an early return to civilian rule.
However, the junta says it will stick by the country's commitment to hosting the 2025 cup.
In March, Doumbouya named a fresh organising committee after one of its members publicly doubted whether the scheme was feasible.