“We have a high level of threat and we also have a particularly high level of mobilisation and vigilance,” Hollande said, expressing his “solidarity and compassion” with Germany.
France, which has been rocked by a series of deadly jihadist strikes over the past two years, “knows… how important it is to be united” in the face of terror attacks, he said.
“That goes for a single country when it is attacked and for all of Europe and the entire world, faced with the terrorist threat,” he said.
Hollande said French authorities had already ordered that security be beefed up over the holidays “at all locations as far as possible, in particular Christmas markets and other gatherings.”
Interior Minister Bruno Le Roux earlier urged the French to “enjoy themselves” but also be careful when celebrating Christmas and the New Year.
“We will ensure the security of our territory and citizens,” Le Roux, who visited France's best-known Christmas market in the eastern city of Strasbourg, near the German border, told Europe 1 radio.
Soldiers have been patrolling the streets of French cities since last year's November jihadist bloodshed in Paris.
Last month, French police broke up a jihadist terror ring which was allegedly planning to attack Paris on December 1 and had researched a Christmas market on the prestigious Champs-Elysees avenue among its potential targets.