The torah requires that monetary disputes be adjudicated by a beis din, rabbinical court. It is permissible to exert social pressure on an individual to convince him to agree to participate in a din Torah (court case) before a beis din. However, social pressure that could cause embarrassment is not an option if the person is in the category of amisecha, your fellow. A person who erroneously believes that he is justified in taking someone else’s money must be set straight, but he is not a mumar (rebellious sinner). Embarrassment is not a recourse, but one may discuss the matter with anyone who can influence the person and explain that the person is involved in a monetary dispute and should be persuaded to come before a beis din. The beis din itself may publicize the fact that an individual refuses to abide by its ruling or ignores a summons to appear before it.
Sefer Chofetz Chaim, 4 Kislev, Page 176