You can restrict user navigation by disabling the player navigation controls. If you lock them, navigation will be disabled in the following areas:

 

In player, when your mouse pointer is over the Outline or navigation buttons, you will see the lock icon on them. Users won't be able to move to the locked slide.
Note: Even if navigation is locked, users can navigate to another slide on click or automatically.
Disable Automatic or On-Click navigation, if you want to completely restrict user navigation.