This paper presents a novel distributed task assignment algorithm to solve the conflict issue of unbalanced task assignment, in the collaborative interception scenarios of unmanned aerial vehicles (UAVs). Considering a single-hop range of communication within multi-UAV, a cooperative task assignment method for the interception of distributed UAVs is proposed, which called Iterative Consensus Task Assignment Algorithm (ICTAA). The method schedules the unbalanced auction selection to contribute multi-to-one assignment problems, with the remaining values of targets across multiple iterations. Meanwhile, an iterative consensus conflict resolution rule based on the Consensus-based Bundle Algorithm (CBBA) is performed to achieve consensus conflict resolution in cases of unbalanced distribution. Experimental results show that the designed algorithm achieves distributed UAVs task assignment for unbalanced scenarios, and gets the second-optimal assignment results with low computation and communication complexity comparing with the centralized algorithms.