Lars Vilks told The Associated Press a man in the front row ran up to him and head-butted him during the lecture at Uppsala University. Vilks says his glasses were broken but he was not injured. It wasn't immediately clear what happened to the attacker.
Vilks said a group of about 15 people had been shouting and trying to interrupt the lecture before the incident.
Many of them stormed the front of the room after the attack and clashed with security guards as Vilks was pulled away into a separate room, he said.
Swedish news agency TT said police detained two people during the commotion. Uppsala police declined to comment.
Vilks was giving a lecture about the limits of the freedom of expression in the world of art.
The Swedish artist says he has received repeated death threats over his drawing of Muhammad with a dog's body.
A US woman faces a life term on accusations that she pledged to murder Vilks. Colleen LaRose, was arrested in Oct. 15 upon returning to Philadelphia from Europe. She has pleaded not guilty to a four-count indictment.
