Come back later when I've done all my chores.
I know you want to talk, but right now I need to focus on my duties.
I'm sorry I can't talk right now. We'll talk a little later.
Unfortunately, right now my attention is completely consumed with work.
Maybe we can talk a little later when I'm free.
Maybe we can talk a little later when I'm done?
My work requires my full attention at the moment.
I know you want to talk to me, but I'm in the middle of something.
I'm sorry, but I can't be distracted right now.
I have a lot of pressing matters at the moment. Our conversation will have to be postponed.