Elon Musk said Apple had halted most of its Twitter ads and accused the company of threatening to remove the platform from its app store.
The row comes as many companies have halted spending on Twitter due to concerns over Mr Musk’s content moderation plans for the site.
Apple did not respond to requests for comment from the BBC.
Mr Musk said Twitter had seen a “massive” drop in revenue, accusing campaigners of pressuring advertisers.
In a series of Tweets on Monday, he accused Apple of “censorship” and criticized its policies, including the fees it takes from purchases made on its App Store.
“Apple almost stopped advertising on Twitter. Do they hate free speech in America?” he said
Musk, who bought Twitter for $44 billion last month, is under pressure as some companies halt spending.
He said he hoped to make money by turning Twitter verification into a paid subscription service, but currently, the vast majority of the site’s revenue comes from advertising.
The Washington Post reported that Apple was the top advertiser on Twitter, spending $48 million on ads on the social network in the first quarter of 2022.
Companies such as Cheerios maker General Mills and Volkswagen are among those that have halted spending in recent weeks.
Media Matters, a monitoring site, reported last week that half of Twitter’s top advertisers had pulled their advertising on Twitter after concerns over Twitter’s management.
Apple’s media agency, Omnicom, has recommended that the Silicon Valley giant suspend advertising on the platform out of concern for Apple’s “brand safety”, according to US tech site The Verge.