The presidents from five West African countries held talks all day with various parties to try to end the political stalemate that has rocked the country and raised fears it could undermine a regional fight against Islamist militants.
"We have decided that we will report back to all the heads of state during an extraordinary meeting on Monday July 27," said Mahamadou Issoufou, Niger's President and current chair of the 15-member regional ECOWAS bloc.
"ECOWAS will take strong measures that will contribute to the resolutions of the crisis," Issoufou told journalists after the meetings.
Infuriated by corruption, disputed local election results and army losses to jihadists, tens of thousands of people have taken to the streets in recent weeks, sparking clashes with police in which the United Nations says at least 14 protesters have died this month.
The opposition, a group called M5-RFP whose figurehead is Saudi-trained Muslim cleric Mahmoud Dicko, has said it will not quit until President Ibrahim Boubacar Keita steps down, raising concerns in neighbouring countries of a protracted crisis.
Dicko told journalists after a final meeting late on Thursday that there had been no progress, and nothing had been offered at the moment that was acceptable to them.
"M5-RFP demands the resignation of Keita or the satisfaction of our demands," which include the establishment of a committee of inquiry into civilian deaths and a transitional government, the group's spokesman Nouhoum Togo had told Reuters on Thursday.
Niger's Issoufou said however that ECOWAS drew a red line on the demand for President Keita to resign.
"There will be no unconstitutional change of power in the ECOWAS region," Issoufou said.