Answer:
Using an interpretive question to try to learn your purpose
Step-by-step explanation:
Interpretive question is being asked when we want to find out what lies behind something that someone said or did. They are mostly used when we want to keep the discussion going.
In the given situation, since the acquaintance does not understand, he, by asking you what are you intending to communicate, wants to find out what lies in the back of your action with a goal to learn your purpose, in other words he wants to understand what were you trying to express with that specific hand gesture.