To playfully invite for you to participate in conversation further, so that I may humbly learn from you. "I don't know what you're talking about" seemed too spartan and austere and aggressive, and you reciprocated politely, if again sparsely, when the other person playfully invited you to elaborate.
Well, you've now made your original intent specific, but in case you didn't draw the requisite lesson I'll make that explicit.
Because text has less bandwidth than almost any other medium, certain forms of humor are much more likely to be understood (in this case, your "gentle playfulness" was taken to be snark, sarcasm, and point scoring).
If you insist on using this and similar forms of humor that, ordinarily, depend quite strongly on intonation to convey intent, you'll have to be much more explicit to avoid being misunderstood. You are going to have actually state your intent explicitly as part of your communication. This need not entirely destroy the humor, for example, you might try something like this:
And so I say to you (playfully, sir, playfully): etc.
Or this:
Yadda yadda yadda. (I kid, I kid!)
The Internet-native forms of this are the humble ;-) or the newer j/k, but I find that it is all too easy to overlook a 3-character sequence, particularly if the passage being so marked is even as long as a single paragraph, but they can serve their purpose when used for the commonplace one-liner.
