Calgary Mayor Naheed Nenshi says he's sorry for calling the CEO of Uber a "dick" in a widely circulated video recorded without his permission recently while he was using a competing ride-hailing service in Boston. But he won't back down on the issue of driver screening, Nenshi wrote in a blog post Saturday.

The Calgary mayor raised eyebrows on Friday when a Periscope video of the rant was obtained by Calgary media. It shows Nenshi complaining about Uber management to his driver, who works for Lyft, another U.S.-based ride-hailing service.

"They are honestly the worst people in the world. I have never dealt with people like this before," Nenshi said of Uber officials.

Calgary Coun. Evan Woolley, a staunch Uber supporter, responded by calling the mayor's remarks "simply a slip of the tongue."

Nenshi dialed back the rhetoric Saturday but stood firm on some of what he said in the video.

"I apologize to Travis Kalanick, CEO of Uber, and his employees for my being, well, a jerk," Nenshi wrote.

Screening comments stand

He added, though, that Uber's driver-screening process is still not up to the City of Calgary's standards.

"As I announced publicly earlier this year, the city became aware of at least one driver who passed through the background check used by Uber in Calgary despite having an active assault charge against him or her."

Nenshi said in the video that a registered sex offender had passed Uber's theoretical screening. But he backed down from that comment in Saturday's blog post.

"I am not aware of anyone convicted of a sexual offence clearing the background check used by Uber in Calgary," Nenshi wrote. "Watching the video, I realize that I did not explain myself clearly at all. I apologize for any confusion that I have caused."

Nenshi said while he was not aware he was being recorded, "that's not the point."  

"One should be the same person in private as in public and I take full responsibility for my interaction with others."

With files from Andrew Brown and Drew Anderson