Speaking about a war against Islamic State only helps the group behind last Friday's bloody attacks in Paris, German Vice Chancellor Sigmar Gabriel said on Tuesday, putting himself at odds with French President Francois Hollande.

Hollande told French parliamentarians on Monday that "France is at war", after the militant attacks that killed at least 129 people in and around Paris.

However, Gabriel, a Social Democrat (SPD) whose party is a natural ally of Hollande's Socialists, said talking about war would only fuel angst in Germany.

"We see that IS is waging war against the free world," Gabriel said in a podcast, referring to Islamic State, which has claimed responsibility for Friday's suicide bombings and shootings.

But speaking about a war against Islamic State was a first step to helping the group succeed, "as the greater the anxiety in our society, including anxiety about war, the more terror can point to success," he said.

Gabriel rejected comments from Bavaria's conservative finance minister, Markus Soeder, who has said the Paris attacks change everything.

"The attacks do not change everything, just the opposite: now we must stand together and show that peace, democracy and the right of every human being to life stands and that we will defend this freedom," he said.