Firstly I equate making fun with teasing. I won't say anymore after this post, but I want to just explain the quote a little more and then I'll drop the subject.

As to the quote I posted, it shows Elinor is not inclined to check her sister, or outwardly make statements about the way Marianne expresses her sadness, however overwrought or ridiculous. Elinor's only object in that passage is to get her to not seclude herself because she's worried about her. This is evidence of how Elinor protects other people's feelings. Actually, there is evidence throughout the novel of her protecting others' feelings. She governs her own feelings, and does what needs to be done with Fanny, Mrs Jennings, Lady Middleton, however little it satisfies her own feelings.

BTW the emphasis on mind in the quote was in the text(not mine).

So while we, the readers, are meant to see the irony of affectionate principle, it does not seem in character for Elinor to try to convey some extra meaning, however twinkly, to Marianne in that particular passage (ch.4 conversation).