The attack in Grande Borne, a run-down residential area built in the 1960s in the southern suburb of Viry-Chatillon, was "unspeakable and intolerable because it endangered the lives of officers whose job was to protect the population", Hollande said.
"Everything will be done to find the perpetrators of this attack and bring them to justice so they receive a sentence in keeping with the severity of their crime," he added.
Prime Minister Manuel Valls said two officers "were violently attacked with incendiary bombs while they were on a surveillance mission in the Grande Borne high security zone".
"Their colleagues who came to back them up were also targeted," he said, describing the attack as "extremely serious and very cowardly".
Police sources described the weapons used as Molotov cocktails. They said two of the officers were rushed to hospital with “major burns”.
Alliance, a police union, told RTL radio that one of the officers was “between life and death”.
The traffic light where the attack occurred has frequently been the scene of violent robberies.
Police scrambled reinforcements to the site on Saturday but no arrests were made.
Valls said the culprits would be "relentlessly pursued and brought to justice. At a time when the security forces are bravely responding to the (terrorist) threats facing our country, such intolerable acts call for exemplary sanctions".
The local mayor, Jean-Marie Vilain, said the response to chronic criminality in the area would be stepped up.
"The next step will be to go inside Grande Borne to put an end to all the drug dealing, because that is really what the cameras interfere with," he told reporters