Is there a way to disable biters from attacking rails?

Negative, there currently isn't a way to disable that behavior.

https://mods.factorio.com/mods/Ranakastrasz/Invulnerable%20Rails%20and%20Poles

Its kinda a Prototype, but it does work. Might have issues with other mods, and if you remove it, they stay invulnerable/neutral (But you can still mine them)

It works in my game at least.

I have a basic version of the rail safety stuff in the mod options for Rampant.
You will need to toggle Enable Building Safety, then pick whatever buildings you want to make safe.

Aww they attack rails? That's a problem.

That is what the options are for, a better method is possible if the factorio devs fix indestructible targeting.

Can there be a custom blacklist of safe buildings? Example: Bob's Mods have several tiers of power poles. Would those be safe from attack or just the vanilla ones?

There could be, I don't think the form would like very nice with the current version of the mod options. The mod option field would end up being a string with a comma delimiter that took in entity types and a different field that took entity names.

Depends on if the type or name is registered with Rampant.

Also using the forums is preferable, as these don't send notifications when you send a message

Hello, i tried to used the safety building option with all checked but bitters still attack rails or poles. Maybe less (not sure about that) but it's really annoying. Do you have or know some solutions ?
In vanilla game (0.15.x) bitters never attack poles or rails, why they do this in this mods ?
Thanks for this anyway, it's really cool :)

currently the only way to make a entity safe is by regenerating it after it gets destroyed. In 0.15.13 a fix has been made to allow for more robust handling of this issue.

They attack poles and rails because I move the unit groups using attack area commands instead of moves.