Randall Rothenberg, president and chief executive officer for the Interactive Advertising Bureau, drew criticism for a fiery speech on Monday during which he took ad-blocking companies to task for being “profiteers” standing in the way of free speech. And he’s not backing down.

The IAB chief, whose trade organization represents companies across the advertising industry, delivered a keynote during its annual leadership meeting in Palm Desert, Calif. After spending some time praising the group’s new officers and urging the industry to hire more minorities, Mr. Rothenberg fired off some heated language. He accused ad-blocking companies of being exploitative, disingenuous crooks who threaten the media business, the future of American journalism and even freedom of speech.

Here are some highlights from his talk, explaining why he hates “the ad-block profiteers”:

•“Adblock Plus is an old-fashioned extortion racket, gussied up in the flowery but false language of contemporary consumerism.”

•Ad-blocking companies are “self-proclaimed libertarians whose liberty involves denying freedom to everyone else.”

•Ad-blocking companies’ “technologies indiscriminately obstruct competitive pricing data, information about product features, vital political opinions, site content, user options, public interest communications, and other intelligence necessary for the functioning of democratic capitalist societies.”

In response, Ben Williams, operations and communications manager for Adblock Plus, provided a statement, looking to present his company as a friend to the digital ad industry.

“As ever, we remain interested in discovering better, more sustainable ways for publishers and content creators to get paid,” Mr. Williams wrote. “And we invite anyone and everyone to join us in doing so.”

CMO Today caught up with Mr. Rothenberg, wondering if he may have cooled off following his keynote. He had not.

“I just wanted to bring truth to the B.S.,” he said in an interview. “There is nothing loaded in the language I used at all. It’s very straightforward. [Ad-blocking companies] are engaged in for-profit businesses and have gussied up what they are doing in the language of false consumerism.”

Mr. Rothenberg said he believes that ad-blocking companies are trying to provoke him and the IAB. For example, last week Adblock Plus said in a public blog post that its representatives had been disinvited to the IAB event, though Mr. Rothenberg says the company was never invited in the first place.

Regardless, Mr. Rothenberg says he can’t hold back when the stakes are so high. Adblock Plus reported that 15 million Americans had downloaded its software in November, and last summer, Adobe and the Dublin-based company PageFair predicted that publishers were set to lose nearly $22 billion in 2015 because of ad blocking, a 41% jump from 2014.

“They are engaged in an intellectually false and morally corrupt exercise,” Mr. Rothenberg said of ad-blocking companies. “Advertising is the form of monetization that has freed the media from the dominance of the state. It supports the diversity of the press…and these ad companies make money on trying to shut that down.”

Mr. Rothenberg didn’t stop there. “These ad blocking companies are little piss ants,” he said. “They are run by a handful of people with silly titles and funny walks who are individually irrelevant…[and are] diminishing freedom of expression.”

Some ad-blocking companies let Web publishers pay to be placed on “whitelists.” Essentially, paying to be on whitelists allows these publishers to make sure their ads aren’t blocked via ad blockers.

“If you pay them, your ads get through. How does that serve consumers?” he asked.

In his speech on Monday, Mr. Rothenberg did acknowledge that the digital ad industry has to take some of the blame for the rise of ad blocking, arguing that publishers have gone too far in bogging down their pages with ad trackers that slow load times and alienate privacy-concerned consumers. The trade group has organized a new initiative aimed at cleaning up the ad experience for people.

But that admission doesn’t mean Mr. Rothenberg is about to credit the ad-blocking companies. “Even a broken clock is right twice a day,” he said.

Write to Mike Shields at mike.shields@wsj.com