
The order under the nation's Online Criminal Harms Act came after the police observed scams on Apple's iMessage and Google Messages purporting to be from companies such as the local postal service SingPost.
While government agencies have registered with a local SMS registry so only they can send messages with the "gov.sg" name, this does not currently apply to the iMessage and Google Messages platforms.
"Members of the public may assume that messages they receive from accounts claiming to be from 'gov.sg' on iMessage or Google Messages are legitimate because messages sent through iMessage and Google Messages appear alongside and are not easily distinguishable from SMSes," the police said.
Under the order, Google and Apple will need to prevent accounts and group chats from displaying names which spoof "gov.sg" and other Singapore government agencies, or filter such messages out.
The home affairs ministry said Apple and Google have committed to complying with the order, and they urged the public to update their mobile apps to ensure that the latest safeguards are in place.