Yes, you can!
Restrict Content Pro is fully integrated with the WP Approve User and New User Approve. Install either WP Approve User or New User Approve and you will be able to require that user accounts be approved before members are able to log in and access the restricted content.
When WP Approve User is active, pending accounts will display an Approve link in the Restrict > Membership page. Hover over a member's username to see the actions appear and find the link Approve.
For members that have been approved an Unapproved link will be shown:
Members that attempt to access content before their account is approved will be shown a message that lets them know their account is pending approval from a site admin.
Sending An Email When An Account Is Approved Or Unapproved
If you would like to send an alert email to accounts when they are approved or unapproved, you may do that through the WP Approve User settings page:
WP Approve User Options Not Showing Up?
Go to Settings > General in your WordPress settings and enable the Membership option.