There have been bans of missile weapons in the past, but I don't find any indication that there was any particular action against the gastraphetes.
There is indication of a Greek ban on the use of bows during the Lelantine War
During the the Lelantine War that took place between them it is stated
that the two city-states made an agreement banning the use of 'missile
weapons'. If this prohibition of a specific type of weapon is true it
stands unique and would be the earliest example of arms limitation in
The problem with respect to the Gastraphetes is that this ban and war occurred about 300 years before its invention. (Note that this ban, and indeed the entire battle, has been considered by some to be fictional.)
One other ban which did include both bows and crossbows, was enacted during the Second Council of the Lateran,by Pope Innocent II in 1139.
The wounds caused by the crossbow in warfare were however considered
so barbarous that its use except against infidels was interdicted by
the second Lateran Council in 1139 under penalty of an anathema as a
weapon hateful to God and unfit for Christians. This prohibition was
confirmed at the close of the same century by Pope Innocent III Conrad
III of Germany 1138 152 also forbad the crossbow in his army and
kingdom. The employment of crossbowmen nevertheless again became
common in English and Continental armies in the reign of Richard II