Time differential of arrival (TDOA) localization is frequently based on synchronous measurements of arrival time of a signal at different sensors. The synchronization of sensors clocks is presumed in many TDOA based methods. When this synchronization is not available, usually one sensor emits some synchronizing signal to other sensors of the network. However, this emission violates the passiveness of the network. In this paper, an iterative method is suggested which uses no additional synchronizing signal to reduce the offsets of clocks. The proposed method is simulated and it is shown that the method is capable of removing timing errors up to ten percent of total measured differential time in TDOA.