Yesterday in the mall a man selling pastries looked at me while I was walking and moved his arms back and forth like he was imitating me and making fun of me, why do you think he did that?

We weren't there and have no idea. You could have asked him what he was doing.  Or, when in doubt, walk away and ignore the person. If the person was working one of the kiosks, their selling tactics are quite aggressive. They have a limited amount of time to get your attention so that you stop at their kiosk and buy or try what they are selling.

You missed your chance to ask him.

He wanted you to come over to try a sample to sell some pastries...

Or he fell in love at first sight and wanted your phone number.

To give you something to wonder about, isn't that obvious.

You should've approach at the moment like "excuse me is there any problem cause i felt like you're pointing at me somehow"

Due reasons you didn't, and later on, it made your mind busy, but i suggest you to not think about it anymore, it doesn't fix anything! There's more than a few possibilities, it could be anything! (you received some good thoughts) but even maybe you just thought it's related to you! While it wan't,  maybe someone were behind you or anything common! Even if you get your answer, probably you won't find that guy again! So the best suggest i can give is to forget it and keep enjoying life.

It could be worse, you could of walked past a building site and had a bunch of blokes woof whistle and shout out "Alright darling!" whilst wearing their jeans so low that they have more crack on show than a drug dealer. Honestly,  it'll  put you off your sausage roll that you bought from the pastry man with weird arms, who's sounding more attractive by the second...let's face it...at least HE has pastries.