A soft restriction is when travel on a street isn't completely prohibited but is "discouraged". Actually, you can also set it up to prefer certain streets (like truck routes), and that's also considered a soft restriction. You can read more about restrictions here: Understanding network attributes—Help | ArcGIS for Desktop
Essentially, the warning you're seeing just indicates that the facility you created has snapped to a street that has one of these soft restrictions applied to it The analysis should still complete successfully. It's just warning you that some streets you might prefer to avoid have to be used because the facility is located on those street segments. You can just ignore the warning.
But if you don't want the warning, you could get rid of it by doing one of these things:
- If you don't care about the restriction, turn it off (in your Service Area layer properties).
- If you don't want your facilities to locate on streets that have these restrictions, check on the "Do not locate on restricted network elements" option in the Network Locations tab of the Service Area layer properties.
