If you feel it might be right to tell her she's cute, then go for it.
But I would suggest trying to give off hints to her that you like her, like sitting closer to her whenever you can or, if you think she wouldn't get mad about it, light and brief contact, such as brushing up against her arm or something
You could even start giving her hugs, like I do with literally every one of my friends, crush included
But it's up to you what you do