Mobile Ad hoc Networks (MANET) are having dynamic nature of its network infrastructure and it is vulnerable to all types of attacks. Among these attacks, the routing attacks getting more attention because its changing the whole topology itself and it causes more damage to MANET. Even there are lot of intrusion detection Systems available to diminish those critical attacks, existing causesunexpected network partition, and causes additional damages to the infrastructure of the network , and it leads to uncertainty in finding routing attacks in MANET. In this paper, we propose a adaptive risk-aware response mechanism with extended Dempster-Shafer theory in MANET to identify the routing attacks and malicious node. Our techniques find the malicious node with degree of evidence from the expert knowledge and detect the important factors for each node.It creates black list and all those malicious nodes so that it may not enter the network again.