"There could be no negotiations" with terrorists, the French media quoted him as saying in the central French city of Tulle.
Hollande said the hostages were "shamefully murdered" by their captors, and he linked the event to France's military operation against al Qaeda-backed rebels in neighboring Mali. "If there was any need to justify our action against terrorism, we would have here, again, an additional argument," he said.
President Barack Obama said in a statement Saturday that the U.S. stood ready to provide whatever assistance was needed in the wake of the attack.
"This attack is another reminder of the threat posed by al Qaeda and other violent extremist groups in North Africa. In the coming days, we will remain in close touch with the Government of Algeria to gain a fuller understanding of what took place so that we can work together to prevent tragedies like this in the future," the statement said.
In New York, the U.N. Security Council issued a statement condemning the militants' terrorist attack and said all perpetrators, organizers, financiers and sponsors of such "reprehensible acts" must be brought to justice.
In the final assault, the remaining band of militants killed the hostages before 11 of them were in turn cut down by the special forces, Algeria's state news agency said. The military launched its Saturday assault to prevent a fire started by the extremists from engulfing the complex and blowing it up, the report added.
A total of 685 Algerian and 107 foreigner workers were freed over the course of the four-day standoff, the ministry statement said, adding that the group of militants that attacked the remote Saharan natural gas complex consisted of 32 men of various nationalities, including three Algerians and explosives experts.
The military also said it confiscated heavy machine guns, rocket launchers, missiles and grenades attached to suicide belts.