Clearview has already amassed more than three billion photographs from sites including Facebook and Twitter.
They are used by the FBI and Department of Homeland Security and more than 600 other law-enforcement agencies around the world to identify suspects.
In a cease-and-desist letter sent on Tuesday, Twitter said its policies had been violated and requested the deletion of any collected data.
Twitter’s developer agreement policy says: “Information derived from Twitter content may not be used by, or knowingly displayed, distributed, or otherwise made available to any public-sector entity for surveillance purposes.”
According to the New York Times, the Clearview app includes programming that could pair the images with augmented-reality glasses that would allow users to identify the names and addresses of anyone they saw.
Clearview has not yet responded to a request for comment.