French President Emmanuel Macron - who hosted a G7 summit that ended on Monday - said $22m (£18m) would be released.
Brazilian officials gave no reason for turning down the money. But President Jair Bolsonaro has accused France of treating Brazil like a colony.
His defence minister said the fires in the Amazon were not out of control.
Commenting on the G7 offer of aid, Mr Bolsonaro's chief of staff, Onyx Lorenzoni, told the Globo news website: "Thanks, but maybe those resources are more relevant to reforest Europe."
"Macron cannot even avoid a predictable fire in a church that is part of the world's heritage, and he wants to give us lessons for our country?" Mr Lorenzoni added, in a reference to the fire that hit Notre-Dame cathedral in Paris in April.
He also said Brazil could teach "any nation" how to protect native forests.
A record number of fires are burning in Brazil, mostly in the Amazon, according to the country's space research agency, Inpe. President Macron last week described the fires as an "international crisis".
Read More (...)