It is 100% acceptable for Libertarians to be against abortion because it may or may not go against the non-aggression principle depending on your personal opinion
The argument on abortion always melts down to “do you think an unborn baby is a human being.”
If you think the answer is “no,” a legitimate position, then you can say that a woman has a right to an abortion.
If you think the answer is “yes,” also a legitimate opinion, then you can say that a woman does NOT have a right to an abortion.
In the second case, the abortion results in the death of an innocent and unborn child (from a certain point of view) and thus is a clear violation of the NAP.
It is entirely legitimate for a Libertarian to hold either view and I am tired of people pretending it isn’t.
Article from r/Libertarian: For a Free Society