Most organizations undergo a number of changes in hope to have a better performance and efficiency. In new conditions and after change, one serious problem that may arise is dysfunctional conflict. In this field study, we focus on an Iranian Internet Service Provider (ISP) -Fanava company- which has recently experienced a change in its structure. As a result, the link between older departments was changed and new departments such as Sales and Marketing were added. However, in the new system employees were not well-informed about the changes in the organization, especially about their new job-descriptions. Hence, it led to high degree of job-interferences among staff which in turn caused a high level of dysfunctional conflicts in the workplace. In this study we focus on two approaches that would potentially involve in the creation of the conflicts. One approach is the individuals' conflict management styles and the other is communication quality in organization. The results show that among the five conflict management styles, the competing style has a positive effect on the rise of dysfunctional conflict. In addition it is found that the quality of company-wide communication has a negative effect on the rise of dysfunctional conflict. However the effect of other conflict management styles- avoiding, collaborating, compromising and cooperating- and the quality of communication within work-groups, does not have direct effect on dysfunctional conflict.