You've got it backwards. Force is not somehow justified or ruled out by the virtues of one's opponent, but simply by its utility. Claims to the contrary notwithstanding, Israel's use of force gained her nothing in 'Cast Lead' and cost her a great deal. It was a self-destructive act.
Five arrested in anti-terror raids in Sydney (DPA)
from the article: Senior Shin Bet official: Hamas completely lost Gaza war