can not add a branch permission for only write maste branch via pull request.

[Fausto Ramon Rodriguez Ruelas]

i am trying to cofigure a restriction for Prevent Changes without a pull request(left Image), but in my actual bitbucket settings (right image) is missing that choice. 

[Tyler T]

The image on the left is from Bitbucket Server.

The prevent changes without a pull request on Bitbucket Cloud, you can do the following:

• Add branch 'master' (you already did this)
• Keep Write access blank
• Merge via pull request -> add Everybody or specific groups

After you save, nobody change will be able to write to master directly but it can be updated via pull request.