There have been more than 30 forest fires in France since last Friday, Collomb revealed on Wednesday.
Particularly serious blazes hit Boulou in the Pyrenees mountains and Saint-Cannat and Castagniers in Provence, as well as on the Mediterranean island of Corsica.
Several thousand firefighters have been mobilised to combat them but they were still not compeletely extinguished on Wednesday, although they were under control, he said.
"The cause of the fires unfortunately seems to be often linked to negligence, to inappropriate behaviour, especially during the summe when climate conditions are difficult," the minister commented.
Tweet by firefighters in the south of France
"The small gesture that makes you a big idiot," reads the message on this graphic.
Nine out of 10 forest fires are caused by human activity, the authorities estimate.
The Saint-Cannat blaze, which destroyed 800 hectares of land, is believed to have been caused by a discarded cigarette.
Collomb appealed to French people's civic-mindedness to try to avoid further outbreaks, adding "the consequences can be tragic, like those that recently caused so much grief to the Portuguese people".
Massive fires in the Pedrogao Grande district of Portugal at the end of June caused 64 deaths and more than 250 injuries.