No it isn't.
Not even WHO (World Health Organization) thinks that being trans is a mental illness anymore.
If you still think blindly hating somebody just because they were born as something they had no controll over is "natural", then you might want to step either in your grave or back into that time machine you used to come here from the 50's.
Person A: "Transphobia is perfectly natural."
Person B: "You must be the kind of person to say 'I'm not racist, but...' before saying something very racist."
Jack: I heard Sara has internalizedtransphobia, I don’t get why she hates trans people.
Tom : She doesn’t hate trans people, she just never thought she would be trans and has internalized hate towards herself.
Jack : So she’s not transphobic?
Tom : No, she’s just scared.
If you think those aren't the correct words to my sentence then you're racist, homophobic, transphobic, misogynistic, xenophobic, and antisemitic, and you have no place in the world other than the fact that you should unironically kill yourself.