Former French president Nicolas Sarkozy said the attack on satirical magazine Charlie Hebdo was "a war declared on civilisation".
"Faced with the barbarity, civilisation must defend itself," Sarkozy said today.
About 7,000 French Jewish people left the country last year and have moved to Israel because they did not feel safe.
The aunt of a man killed while trying to overpower gunman Amedy Coulibaly has told ITV News her family is fearful of their future in France.
A Muslim cleric in Pakistan has held a ceremony to honour Cherif and Said Kouachi, the two men suspected of the Charlie Hebdo massacre.