The actomyosin cytoskeleton is a major driver of cell shape change and can be coordinated across neighbouring cells to form assemblies known as cables. Here, Katja Röper and colleagues investigate Zasp52, a protein found in Drosophila striated muscle that was known to localise to an embryonic actomyosin cable during dorsal closure. They find that Zasp52-GFP localises to many other cables in the fly embryo, with loss of zygotic Zasp52 leading to reduced F-actin accumulation in the cable surrounding the salivary gland placode. Binding assays show that Zasp52 interacts directly with F-actin via a previously unrecognised motif, and also interacts with cell junction components such as APC2. Embryos lacking zygotic and maternally deposited Zasp52 exhibit dramatic morphogenetic defects in tissues associated with actomyosin cables. Combining their in vivo observations of cell movements with in silico modelling, they propose that Zasp52-associated cables act as mechanical insulators, preventing morphogenetic events from inappropriately influencing neighbouring tissues. Overall, they uncover a role for Zasp52 in cable function and present a model to explain how cell behaviours can be coordinated during development while maintaining the integrity of distinct tissues.