The Seyni Kountche stadium, the largest in Niger with a capacity of 30,000 seats, was two-thirds full and the sound of vuvuzelas rang out, AFP journalists noted.
The flags of Niger, Algeria, and Russia dotted the stands, while acrobats painted in Niger's national colours put on a show in the centre of the pitch.
"We have the right to choose the partners we want," said Ramatou Ibrahim Boubacar, wearing Nigerien flags from head to toe. "France must respect this choice.
"For sixty years, we have never been independent, only since the day of the coup d'etat," she said.
Boubacar added that the country fully supported the National Council for the Safeguard of the Homeland (CNSP), which seized power after overthrowing President Mohamed Bazoum's government on July 26.
The CNSP is led by General Abdourahamane Tiani, who has made former colonial power France its new target.
"The fight will not stop until the day there are no longer any French soldiers in Niger," CNSP member Colonel Obro Amadou told the stadium crowd on Saturday.
"It's you who are going to drive them out," he said.
'Ready to fight'
On Friday, Niger's foreign ministry announced that French ambassador Sylvain Itte had 48 hours to leave, claiming he refused to meet with the new rulers and citing French government actions that were "contrary to the interests of Niger".
Paris has since rejected the demand, saying that "the putschists do not have the authority to make this request."
"The French ambassador, instead of leaving, thinks this is the land of his parents," said Idrissa Halidou, a healthcare worker and CNSP member who was attending Saturday's rally.
"We are people of war, we are ready to fight against" the Economic Community of West African States (ECOWAS), he added.
The West African bloc has applied sanctions against the new regime and threatened to use military means to remove it if the new rulers do not hand back power to Bazoum.
Efforts to find a diplomatic solution are continuing, however, with Molly Phee, the top US diplomat for sub-Saharan Africa, visiting Nigeria to meet ECOWAS officials.
They met in Nigeria's capital Abuja, which holds the ECOWAS presidency.
The US State Department said Phee was also consulting senior officials in Benin, Ivory Coast, Senegal and Togo -- fellow members of the ECOWAS regional bloc.
The new rulers in Niamey accuse ECOWAS of being in France's pocket.
France has 1,500 soldiers based in Niger who had been helping Bazoum in the fight against jihadist forces that have been active in the country for years.