French President Francois Hollande has vowed that his country willprotect all religions, saying that Muslims are the main victims of fanaticism.
Speaking at the Arab World Institute, he said Islam was compatible with democracy and thanked Arabs for their solidarity over terrorism in Paris.
Attacks on Charlie Hebdo magazine, a Jewish supermarket, and a policewoman killed 17 people last week.
Funeral ceremonies for several of the victims are being held.
Among them are two of Charlie Hebdo's best known cartoonists, Bernard Verlhac - known as "Tignous" - and Georges Wolinski.
'Obligation to protect' Speaking on Thursday morning, Mr Hollande said that the French were united in the face of terror.
"French Muslims have the same rights as all other French," he said. "We have the obligation to protect them.
"The law has to be enforced in a firm way in places of worship like churches, mosques, and synagogues."
"Anti-Muslim and anti-Semitic acts have to be condemned and punished."
Mr Hollande said that radical Islam had fed off contradictions, poverty, inequality and conflict, and that "it is Muslims who are the first victims of fanaticism, fundamentalism and intolerance".
Mr Hollande had declared Charlie Hebdo magazine "reborn" after a new edition sold out in hours.
Millions more copies of the magazine are being printed because of demand. On the cover, the issue shows the Prophet weeping while holding a sign saying "I am Charlie", and below the headline "All is forgiven" - an image that has angered some Muslims.
"I am Charlie" emerged as a message of support for both the magazine and free speech following the attacks that started on 7 January.
'Honour of the Prophet' On Thursday, Turkish Prime Minister Ahmet Davutoglu condemned the publication as an "open provocation".
"Freedom of the press does not mean freedom to insult," said Mr Davutoglu, who on Sunday attended a Paris march in memory of the victims of last week's attacks.
"We are determined to protect the honour of the Prophet the same way as we are determined in our stance against terrorism in Paris."
Turkish daily Cumhuriyet and Turkish websites have published images of the Charlie Hebdo cartoon.
In Pakistan on Thursday, lawmakers unanimously approved a resolution condemning the publication of the images, state-run TV reported.
In Germany, Chancellor Merkel addressed a special session of parliament to commemorate the victims of last week's attacks.
She said there was no place for violence and discrimination in Germany and the country would not be divided by attacks against people of any faith.
"Hate preachers, violent delinquents who act in the name of Islam, those behind them, and the intellectual arsonists of international terrorism will be rigorously fought with all legal means at the disposal of the state," she said.
She described those working for integration as "the true heroes of democracy".