Based on Event System Theory, this study investigates conflict event strength, which represents how team members interpret conflict event as the reason for withholding effort. In this study, we identify the impact of conflict event strength on withholding effort. At the same time, as a way of changing the effect of conflict event strength on withholding effort, we examine the cross-level effects of peer monitoring and team conflict management. The data are collected 127 employees from 37 teams, and the multi-level model was tested. Results indicated that conflict event strength was positively related to withholding effort. Also, peer monitoring which is first team-level variable moderated the relationship between task/relationship conflict event strength and withholding effort. Interestingly, we hypothesized that the peer monitoring cause employee’s psychological reactance when relationship conflict event strength is high, which in turn reinforce withholding effort, but the result shows exactly the contrary effect. The second team-level variable, which is team conflict management, only moderated the relationship between task conflict event strength and withholding effort. Based on these findings, the limitation and suggestions of the research and the direction for future research were discussed.