• Elon Musk reinstated the account of former President Donald Trump over the weekend based on an informal poll he ran on Twitter.
• On Tuesday, Musk said "a large coalition" of activist groups "broke a deal" with him, implying they'd promised not to encourage advertiser boycotts.
• NAACP CEO Derrick Johnson said the civil rights group "would never make such a deal."

Leaders of major civil rights groups are denying accusations made by Elon Musk, who said they broke an agreement with him by encouraging companies to halt advertising on Twitter.

Musk tweeted on Tuesday that "a large coalition of political/social activist groups agreed not to try to kill Twitter by starving us of advertising revenue if I agreed to this condition. They broke the deal."

A large coalition of political/social activist groups agreed not to try to kill Twitter by starving us of advertising revenue if I agreed to this condition.

They broke the deal.

— Elon Musk (@elonmusk) November 22, 2022

Musk didn't elaborate on the agreement. He was responding to one of his followers, who accused Twitter's new owner of lying when he promised in October that he would form a content moderation council and that "no major content decisions or account reinstatements will happen before that council convenes."

Over the weekend, after running an informal poll on Twitter, Musk and the platform reinstated the account of former President Donald Trump, who was permanently expelled under previous management after the Jan. 6 insurrection on the U.S. Capitol.

Twitter leadership in 2021 feared Trump's presence and ongoing use of the site could lead to further violence as he continued to falsely claim that the 2020 election was stolen from him.

Earlier this month, multiple civil rights groups urged advertisers to pause advertising on Twitter following a spike in hate speech on the site and after the company laid off thousands of employees, a move they feared would impede the company's ability to moderate hateful and other problematic content.

Derrick Johnson, CEO of the National Association for the Advancement of Colored People, said in response to Musk's claims on Tuesday that the civil rights groups "would never make such a deal" and that "Democracy always comes first."

"The decisions being made at Twitter are dangerous, and it is our duty, as it has been since our founding, to speak out against threats to our democracy," Johnson said. "Hate speech and violent conspiracies can have no safe harbor."

In a statement to CNBC, the Gay & Lesbian Alliance Against Defamation and Free Press echoed Johnson's sentiment and said there was "no such deal" with Musk.

"Musk is losing advertisers because he's acted irresponsibly, slashing content moderation teams that help keep brands safe and gutting the very sales teams responsible for maintaining relationships with advertisers," the Free Press said in a statement. "The main person responsible for the Twitter advertiser exodus is Elon Musk.

Rabbi Abraham Cooper, associate dean and director of global social action agenda at the Simon Wiesenthal Center, told CNBC that he found Musk's tweet "vague." The SWC, along with 180 other nongovernmental organizations, sent a letter to Musk last week urging Twitter to adopt the International Holocaust Remembrance Alliance's definition of antisemitism to "degrade the marketing capabilities of antisemites on the social media platform."

Cooper said the letter "wasn't a threat" and that the groups didn't "threaten any boycott" against Twitter.

"We're basically asking Elon Musk, who we all know is a rather creative person, to take leadership in this area," Cooper said. He said his organization has seen a noticeable increase in antisemitic content over the past two weeks.

According to Twitter internal communications obtained by CNBC, agencies and brands that paused advertising on Twitter after Musk took over the company are now waiting for updates on changes to company leadership, specifically teams working on brand safety. They also want answers to questions about how Twitter Blue verification will work in the future and how Twitter plans to prevent brand impersonation.

Under Musk's leadership, Twitter rolled out and promptly rolled back a Twitter Blue Verified subscription service, after users who purchased the badges were able to impersonate celebrities, politicians and brands. For example, an account created in the likeness of drug company Eli Lilly published false tweets saying, "we are excited to announce insulin is free now." The company scrambled to correct the misinformation and have the impersonator's account suspended.

Advertisers' concerns are not limited to the issues raised by civil rights leaders. They also wanted reassurances that Twitter will be safe from hackers, with so many employees resigning or laid off, and they're asking for more communication from new leadership about changes to the product and company.

WATCH: Musk says Twitter Blue will relaunch on Nov. 29