There should always be some attraction. The person you're marrying should appeal to you in some way. It's not necessary for them to be very beautiful or handsome because beauty is in the eye of the beholder.
so if you're okay with the person and like their personality, then marry them. but if not, that is, they are attractive but you don't feel any attraction to them, it may simply be because you are not happy with the idea of parents suggesting someone. In that case, you should think of it as just that, your parents introducing you to a person just as someone else may do so. for example, a friend may introduce you to someone or you may meet someone at college, which is really the college introducing you to someone. and so, you shouldn't make an issue out of parents introducing you to someone. it may be something you are not used to but it's normal and nothing to worry about.
if the person is attractive and their personality is likeable, you shouldn't refuse just because it's an arranged marriage. insha-Allah with this mindset, you will open up and see the person in true light and eventually, before or after marriage, you'll develop attraction. But if you look at the subject with a closed mind (if you see it as something inappropraite, something that can't possibly work) you'll never give the person a chance and will never see the person in true light. you'll feel dislike towrd the person for no reason and the results will not be good. this is simply because current day society has taught us that we should ourselves find a spouse and recommendation by parents is not the way to find a spouse. but is wrong, because even in the wester society, someone is always recommending someone. friends will introduce them, ppl go on blind dates, ppl use datng agencies, etc. If such work then why can't you meet your spouse through parents / family?
on the other hand, if the person is not attractive or their personality is not likeable, then it might be better for you to not marry them because you may never develop attraction, and the marriage will be doomed.