In multiple real life situations involving several agents, cooperation can be beneficial for all. For example, some telecommunication or electricity providers may cooperate in order to address occasional resources needs by giving to coopetitors some quantities of their own surplus while expecting in return a similar service. However, since agents are a priori egoist, the risk of being exploited is high. In this work, we propose to model this kind of situations as a social dilemma (a situation where Nash Equilibrium is non optimal) in which each agent knows only its own state. We design an algorithm modelling the agents whose goal is to make transactions in order to augment their own utility. The algorithm needs to be robust to defection and encourage cooperation. Our framework modelling each agent consists in iterations divided in four major steps: the communication of demands/needs, the detection of opponent cooperation, the cooperation response policy and finally the allocation of resources. In this paper, we focus on the cooperation response policy. We propose a new version of tit-for-tat and we evaluate it with metrics such as safety and incentive-compatibility. Several experiments are performed and confirm the relevance of our improvement.