Oil and Gas offshore pipelines, often pass through large geographical areas, from the supply point to the end-user, crossing seismic-active areas. For unburied pipelines, both seismic ground wave and permanent ground deformation can cause severe damage to pipelines, depending on the pipeline geometry and connected structures. Due to the largely non-linear nature of the problem, a finite element analysis (FEA) is the most general tool for sub sea pipeline design under seismic loading. Throughout this research, the responses of an offshore unburied pipeline resting on the seabed in shutdown and operation conditions will be investigated under various earthquake loading including various types of seismic faults (strike-slip, Normal, reverse and oblique) and also seismic ground wave propagation for Probable Persian Gulf earthquake magnitudes. The pipeline integrity regarding operation criteria in critical conditions will be assessed. In addition, effects of two different site soil properties and pipeline end restraint on pipeline behavior will be investigated.