Unfortunately as far as I know your options are pretty limited. The only way I'm aware of that you can do this is by adding the following line at the very of the actor code (before </actor> of course).
<collision static="true" collision-response="false">
<circle offset="0 0" radius="4" />j
</collision>
This will also make so your actor can't move, that's the downside, hopefully that works for you. It doesn't work if you change it to collision static="false" unfortunately. You can try inserting the collision-response="false" into random areas in actor behavior and you might get something since that's what makes it not register but I didn't have any luck with that.