Meet up with her personally and say it to her face. Maybe she is not mad, but trying to figure out whether the whole thing is true. Face to face dialogue would be the best since you will truly tell how she feels from her reaction.
Maybe she thought you were a true friend not trying to get a date or more off her. She may be angry that you have altered what she has with you. She may feel uncomfortable now around you. Give her space & apologize if it made her uncomfortable & ask to still be friends but move on in the love department.