The army has stepped into a power vacuum left by Compaore, who was forced to resign last week in the wake of violent demonstrations over attempts to extend his 27-year-rule.
The Burkina military has named Lieutenant Colonel Isaac Zida as interim head of state, sparking angry protests and prompting threats of sanctions from the international community.
Zida has claimed that "power does not interest us" and pledged to install a unity government with a "broad consensus".
"After that period we are going to apply sanctions," said Simeon Oyono Esono, head of the AU's Peace and Security Council.
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"The African Union is convinced that the change has been against democracy."
Washington said it was still "gathering facts" on the situation but could yet withdraw its USD 14 million annual aid package to Burkina Faso.
Former colonial power France said yesterday it hoped for an announcement on the return of civilian rule "in the coming hours".
Hollande also said France had been in direct contact with Compaore prior to his ouster last week.
"I made a statement on Friday asking Blaise Compaore to make the right decision, that is to leave," said Hollande, adding that France had intervened to ensure he escaped "without drama" although its personnel did not directly participate.
Compaore and his wife have taken refuge in neighbouring Ivory Coast where they are being put up in a luxury government mansion in the capital Yamoussoukro.
He gave no timetable for the transition but said he wanted a new regime in place within the "shortest possible" period.
Following protests against the army takeover on Sunday, life was back to normal yesterday in the capital Ouagadougou, with the largest market ending a six-day shutdown and banks open.