During an in-flight press conference Pope Francis spoke on the Charlie Hebdo terrorist attack, saying that freedom of expression has limits but no one has the right to kill in the name of God.

"Let's go to Paris. Let's speak clearly," said Pope Francis in reference to the Charlie Hebdo killings. He was asked by a French journalist if he saw freedom of expression as a fundamental human right.

"You cannot provoke. You cannot insult the faith of others. You cannot make fun of the faith," Pope Francis said during a Jan. 15 press conference held en-route to the Philippines. If you do, he said, you "can expect a punch."

On Jan.7 Muslim extremists entered the headquarters of French newspaper Charlie Hebdo, killing 12 people. They claimed the attacks avenged the cartoons printed in the publication that depicted offensive images of the Prophet Mohammed.

The Pope said that while the Paris attack "astonishes us," in world history wars and atrocities like the Catholic-led massacre "St. Bartholomew's night" incident in France have also come from those who profess religions.

"Also we were sinners in this," he added. "But you cannot kill in the name of God, This is an aberration. Killing in the name of God is an aberration against God. I think this is the main thing with freedom of religion. You can practice with freedom but without imposing or killing."

He said that every person has not just the freedom or right, but also an obligation "to say what he thinks" to build the common good. "We have the obligation to freely have this liberty, but without offending."

Just yesterday at Mass in Colombo, Sri Lanka, Pope Francis categorized the freedom of religion as a fundamental human right. During the airborne press conference called both freedom of religion and expression "fundamental human rights," but said there are limits to the freedoms.

"You cannot offend or make war, kill in the name of your religion, that is in the name of God," the Pope told journalists.

But if the freedom of expression is used to offend, he said, one can expect a reaction.

He used the example of Dr. Alberto Gasbarri, the organizer of papal trips, who was standing beside him during the in-flight press conference.

"It's true that you cannot react violently. But, if Dr. Gasbarri, my great friend, says something against my mother, he can expect a punch. It's normal."

Those who "giocatalizzano," or "make a plaything out of the religion of others … are provoking," he went on. "And, what can happen is what I said about Dr. Gasbarri if he says something about my mother. There's a limit.”

"Every religion has dignity, every religion that respects human life and the human person and I cannot make fun of it. And this is a limit," he added.     

About freedom of religion, he said "You cannot hide the truth. Everyone has the right to practice their religion, their own religion without offending, freely. And that's what we do, what we all want to do."

Referencing rumors that the terrorist group ISIS might be planning a targeted attack on him, Pope Francis answered by saying that he’s not worried, and that the best way to react is always with a “meek (and) humble” attitude “without making aggression. I am feeling that there are some who do not understand this.”

“This worries me, no? It worries me enough. I have fear but I have an effect, a good dose of unawareness. I am unaware of these things.”

However the Pope did express concern for the faithful who might be present if an attack did occur, and said that he has already spoken with the Vatican’s security, who are “charged with solving this.”