Did law-making assembly in Athens consisted of a group of 1000 free adult males?

In short, yes. Athenian democracy was developed around the fifth century BCE and was one of the first democracies in the world. One of the ways for laws to be revised and reviewed was to choose (by lot) a group of 1,000 adult males (Nomothetai), who would vote on any revisions that needed to be made.