This article investigates the impact of data integrity attacks (DIAs) on cooperative economic dispatch of distributed generators (DGs) in an ac microgrid. To establish resiliency against such attacks and ensure optimal operation, a localized event-driven attack-resilient scheme is proposed. Most of the existing works examine neighboring information to infer the presence of DIAs, where the detection is limited to events such as multiple link failures. Two kinds of DIAs are considered in this article-namely, fault and random attacks, which are segregated based on the final values of consensus updates. First, to improve the robustness of the detection theory, a localized resilient control update is designed by modeling each DG with a reference incremental cost. Second, event-driven control signal is generated for the local incremental cost and held upon the detection of attacks, to prevent malicious data from propagating to the neighboring nodes. The proposed strategy acts immediately upon the detection of DIA to ensure maximization in the economic profit. Furthermore, the proposed detection approach is theoretically verified and validated using simulation conditions.