"They were already turned away at the security checkpoint and were never in the lecture hall," Uppsala Police press spokesman Christer Nordström told newspaper Expressen on Thursday.
Nordström did not disclose why the four people were turned away. Late last month, the university invited Vilks to complete his on freedom of speech which he first attempted to give at the university in May.
The initial lecture, however, was interrupted when Vilks was headbutted by a man attending the lecture.
An angry group of about 20 people out of the audience of about 250 students took offence when Vilks showed a film with naked gay men wearing masks depicting the Prophet Muhammad during the May lecture.
Vilks' talk on Thursday touched on themes including violence, cruelty and injustice, and demarcating borders within the art world.
”In many ways, it has a very fitting title,” he told the audience.
The lecture hall was filled with spectators, including many journalists, as well as a large number of security guards and police.
Journalists and audience members lined up in the rain on Thursday as they waited to pass through security checks at the entrance.
The police presence was substantial, which about 130 officers dispatched to the lecture. Barricades were also erected as an extra precaution against possible disruptions.
The cost of the operation was estimated at 700,000 kronor ($104,907), according to news agency TT.
The expenses include the security guards responsible for checking identification and the x-ray machines at the entrance. Those costs will be covered by the university and are estimated at 50,000 to 70,000 kronor.
"This is a part of my daily existence. But when it's a public event like this, it can easily cost that much," said Vilks after his talk.
The event's comprehensive security arrangements included identity checks and x-ray machines, resulting in long lines to enter the hall.