Jaggies on image plane

I made my render just to realize that edges (of the alpha) on the various image planes are very jaggy and flickering, I have the feeling that I'm rendering in unreal engine.

Is it the alpha the problem or is there any aa setting I could enable or tweak?

Thank you for helping.

Enable supersampling in your renderer (OpenGL)

Thank you marc
I was using using the renderer at default, and didn't even noticed the settings yet. lol