In relation to Habermas, other sociologists who discuss aspects of social interaction are Karl and Max Weber.
Weber's sociological focus was antipositivist which means that he did not just look at how external social forces (economics and class struggle) affected people. His approach was less empirical, more subjective. Unlike Marx, who believed that material conditions were the primary forces of history, Weber looked at ideas and the ways individuals thought about the world. Both Marx and Weber are considered highly influential to the field of social interaction and to the Frankfurt School, of which Habermas was a member of the second wave. Auguste Comte, sometimes referred to as one of the founders of sociology, is definitely a precursor to Marx, Weber and then Habermas.
B.F. Skinner was more of a behavioral psychologist but his work is interesting for its extreme view that all behavior is conditioned, a theory more closely related to Marx's historical materialism than Weber's antipositivism. On the other hand, it might be interesting to look at agency and intentionality and behaviors that are not merely the effects of conditioning. Edmund Husserl is the most famous philosopher of intentional consciousness. And there are other philosophers and sociologists who talk about agency in terms of thought and action. Michel Foucault studied the spaces (compare with Husserl's lifeworld and Habermas' public sphere) of power and resistance. Foucault also studied the structures of power and how they affected individuals and societies as a whole.
Anthony Giddens, a more contemporary sociologist than those already mentioned, is known for his theory of structuration which considers to what extent individual agency and social/material forces play roles in shaping society.
Other sociologists look at how gender (Simon de Beauvoir) and race (Cornell West) construct social roles and how those roles interact.