The Cyberspace Administration of China said on its website that the two companies had engaged in Internet news information services without obtaining the correct licences, and collaborated with international news services without conducting security assessments.
It did not provide more details on the violations but said that heads of the two websites were called into meetings with authorities from Tianjin, Beijing, Jiangsu and Shanghai where they were told to stop those activities.
A statement posted on the website of Visual China, China's largest stock images provider which is sometimes likened to U.S. photo agency Getty Images, said that it had suspended services to carry out "self-rectification" at the request of the authorities.
Imaginechina's website carried a similar statement. ByteDance, the owner of popular short video apps TikTok and Douyin, invested in Imaginechina in 2016. ByteDance did not immediately respond to a request for comment.
Political control of the internet has tightened under President Xi Jinping, with demands that companies tighten oversight of "harmful information" which could range from vulgar to politically sensitive content.
Visual China also temporarily shut its website in April to make changes after it was criticised online and by regulators for selling images which it did not hold the ownership rights to, such as China's national emblems including its flag.
By Brenda Goh