The ban is a response to an executive order from President Donald Trump. The Department of Commerce announced last week it would prohibit transactions on mobile apps WeChat and TikTok.
The order was to come into force on 20 September. A group of WeChat users filed a lawsuit against the action hoping to delay or block the motion.
US magistrate judge Laurel Beeler ruled in favour of the group. In her order she describes the prohibitions as a substantial burden on First Amendment rights.