An IoT-D2D cooperation framework for task allocation among objects in the IoT (Internet of Things) is presented. Proximity Services based on Device to Device (D2D) communication are used to enable direct interaction between IoT objects. The process is triggered by a node that decides to set up a cluster of nodes and then to coordinate the allocation strategy, where objects capable of performing the same tasks compete to get relevant remunerations. We then propose a game-theory based approach to find a solution maximizing objects utility functions. We prove that a Nash Equilibrium Point (NEP) can be found. Experimental results provide insights on the strategy performance