Doubtful.
Godzilla himself is not large enough to be the cause of anything like a tsunami, as those take such tremendous forces as the movement of the tectonic plates and underground earthquakes resulting from said shifting plates. Godzilla is also not large enough to cause devastation on a such a widespread scale as a tsunami. His path of destruction is much more linear given that he can only take up so much space at one time as opposed to a tsunami which can cover literally miles from end to end.
Realistically speaking, Godzilla could cause as much damage as a tsunami given enough time, but for short term effect the tsunami has him beat.
