Dear cisgender people,
Let me preface this by saying, I'm sure this will be an unpopular opinion. It's a complicated subject but I will do my best to give you my perspective as a transgender person on cisgender people's "sexual preferences" for not being attracted to trans people.
This isn't about forcing anyone to be attracted to anyone or have sex with anyone. This also isn't about someone without genital repulsion, which is valid.
However, your %100 exclusion of trans people is a bit problematic. Here's why:
You assume everyone attractive is automatically cisgender. You are attracted to trans people, you just might not know they're trans. This "preference" of only being attracted to cis people operates under the assumption that you know who is cis and who is trans just by looking at them. That is transphobic.
Assuming that every person you meet and are attracted to is cisgender, and then saying "Well I was really attracted to you, but now I'm not solely because you're trans." is transphobic because it's not that you just don't find trans people attractive, it's that you did find them attractive until you "found out" they're trans. When you say you could never ever be attracted to a trans person, you're also saying, by default, that trans people are unattractive, when we just established that many trans people "pass for cis".
I could say "I have a preference for white men." and that would be a preference, but if I said "I could never ever be attracted to a non-white man. Every non-white person who has ever lived, is living, or will live, I have no possibility of ever being attracted to." Sounds pretty racist, doesn't it? If I meet a man who I find attractive in every single way, except for the fact he's black and decide not to date him, that's racist. That's also assuming that I can always tell who is non-white by looks alone. You could have a preference for brown eyes, but that doesn't mean if you found a green-eyed man attractive you would refuse to date him, would it? I understand though that having a certain kind of genitals is more of a deal breaker than having green eyes (for some). If it doesn't work for you, it doesn't work, but-
It doesn't mean you were tricked.
No trans people are "tricking" you. No trans person doesn't say "I'm trans" before the pants start to come off. It just doesn't happen. But assuming what someone has in their pants based on their appearance is transphobic, anyway.
You should also be aware that your genital preference is rooted in an unconscious cisnormative brainwashing. Hypothetically, you're only attracted to men, and only attracted to penises. That's because you've been conditioned to associate penises with men. You may believe that transgender men are real men, but your subconscious "preference" for penises as the defining factor for your sexual attraction to men, is transphobic.
If you say "I'm attracted to men, but never transgender men." in a way, you are saying that transgender men are not men, based on your omission of them because of their genitalia. Excluding trans men from the category of "men" in your sexuality based not on their gender, but on their genitals, is transphobia. If I go to a men's only gym and they exclude me, a man, because of my genitals, that's transphobic. Attraction may be different from a men's gym, but you understand what I'm trying to say. You're removing us from the category of "men".
I see a lot of videos circulating online from cisgender content creators on why they will never date a trans person, because it's their "preference". But what I don't see are videos called "Why I'll never date a fat person" or "Why I'll never date a black person." They don't say in their videos, "I have a preference for skinny people and I will never be attracted to any fat people so sorry not sorry." or "Here's my video on why I will never be attracted to black people." because they know that there's no point to creating a clearly offensive video for thousands of people to watch that has no other purpose but to make people feel bad. So why is it okay to do it to trans people? What's the point? Transgender people are already marginalized, why go out of your way to make it a point to say they're unattractive to you? Nobody cares.
There are skinny trans people, there are blue-eyed trans people, there are big, small, black, white, tall, short, trans people. So if all trans men of every shape, color, size, and type are all unattractive simply because they don't have the anatomy of a cis man, how is that not assigning genitals to gender?
Now, I'm not saying you have to date a trans person, or have sex with a trans person, or do anything with a trans person. You can have your "preference" for cis people only, nobody is making you like trans people. However, it's important to note that most of the time these "preferences" are rooted in bioessentialism and transphobia, because you're still associating being a man with having a penis.
If you don't want to date trans people, that's fine, but you need to be upfront about it. It isn't the transgender person's hang up, it's yours. It shouldn't be up to a trans person to out themselves to you on a first date just in case you want to change your mind. If you're out on a date with them, you're clearly attracted to them, and it isn't their fault you have a "preference" for cis people. Again, you're the one with the strict "preference", you should be the one to let them know. It's also a safety issue for a transgender person as well, because outing themselves in public to someone they barely know can often end in violence.
So, to wrap this up, I will say that it's fine to have your "cis only" dating preference, but you don't need to scream it from the rooftops how much you don't want to date transgender people, because I can guarantee you, if that's how you feel, we don't want to date you either.
A great video on this topic from Activist Kat Blaque here