It's good that you don't keep calling her back if she doesn't respond to you. If you did, that would be being clingy and stalkerish.

From your post, I take it that you are way more interested in her than she is to you. She thinks of you as a good friend. You think of her as more than a friend. That's the reason you care more about giving her presents and calls than she is the other way around. She already said that she doesn't want to be more than friends with you, so it's best not to push her. If you try to make her like you or keep telling her that you like her, she may want to distance herself from you. That will jeopardize the friendship. If you want to be friends with her, then you'll have to get rid of your deeper feeling for her.