Add [Block Content Permissions] module ( ~1.0 )

Block Content Permissions

https://www.drupal.org/project/block_content_permissions

The Block Content Permissions module allows you to control access to administer block content types (custom block types), administer block content (custom block library), and create, update, or delete specific types of block content.

This module removes the required "Administer blocks" permission from all block content and block content type pages except the "Custom block library - Blocks" views page. There is an open issue for the remaining page.