Second of all, there’s nothing wrong with a ten year age difference in either direction. Lots of couples with ten year age differences do just fine and lots of couples with no age differences break up all the time. So, since you’re 25, and not 18, I really don’t think the age difference has to be a problem.
That said, If she’s not interested in a serious relationship with someone ten years her junior, there’s not going to be a lot you can do to convince her otherwise. Some people just don’t like blondes. Or brunettes, and don’t want to date them. Some people will only date boyfriends or girlfriends of a certain religion or body type. People have preferences and you shouldn’t take it personally.
What you can do is to continue to ask her out, and reassure her of what it is you’re looking for for yourself in a relationship in the long run. If she’s 35, chances are she’s got a biologically ticking clock and may be looking for a potential husband and father of her (your?) children together. If you’re not on board for this then be honest. If you are (and there are plenty of 25 year old guys who are ready to get married and have a family), then all you can do is reassure her of your intentions.
Keep the communication going, ask her out on dates, and be honest with her — and more importantly, yourself. There’s no reason an age gap has to mean anything negative at all.