From 15 April only verified subscribers will have posts recommended to other users and be allowed to vote in polls.
Under the policy, posts from non-paying accounts will not be included in the "For you" stream of recommended tweets.
Last week, the firm said it would remove the verified status of some "legacy" accounts, which date from before Mr Musk bought the firm.
Users currently pay $7 (£5.70) a month for blue-tick verification, which also allows access to additional features.
Mr Musk said the changes were "the only realistic way to address advanced AI bot swarms taking over. It is otherwise a hopeless losing battle."
"Voting in polls will require verification for same reason," he added.
In an earlier post, Mr Musk said paid verification significantly increases the cost of using bots and makes it easier to identify them.
However, the move has been criticised by some social media users.
A former worker on Twitter's verification team who asked to remain anonymous told the BBC: "Our number one goal for my team was to protect users from real world harm and this screams the complete opposite to me."
"Verified users will use their power and their presence on the platform to influence anything from misinformation to actual harm for users all around the world. It's a silent threat that no one is seeing," they added.