On Monday, Elon Musk criticized the fee Apple charges software developers, including Twitter, for in-app purchases, and posted a meme suggesting he was willing to "go to war" rather than pay the levy.
Apple did not immediately respond to a request for comment on Wednesday. It said earlier this week that the commissions it gets help to fund reviews of apps to ensure consumers are not exposed to fraud, pornography or privacy-intrusion.
Spotify has previously submitted antitrust complaints against Apple's policies with the European Commission.
Apart from Musk, Ek also tagged various technology executives in his tweets, from Epic Games CEO Tim Sweeney to Microsoft President Brad Smith.
"So how much longer will we look away from this threat to the future of the internet? How many more consumers will be denied choice?," Ek said in a tweet tagging the European Commission and the U.S. Commerce Department.
"There's been a lot of talk. Talk is helpful but we need action," Ek said.
(Reporting by Supantha Mukherjee in Stockholm and Martin Coulter in London; Editing by Mark Potter)