You say 7 dead vs. 1300 dead therefore Hamas at most 7 dead as a war crime. What you don't include is the dead on the Palestinian side caused by Hamas firing rockets from civilian populations. You also don't include the firing of rockets that are aimed at Israeli civilian populations. Just because they often times weren't successful in killing doesn't mean it's not a war crime. That's like saying attempted murder is not a crime. Finally it was Hamas that has continually targeted civilian populations either with rockets or suicide bombers so the fact that Israel has more fire power to react doesn't make Israel's response a war crime.
ISIS claims responsibility for bombing in Baghdad suburb; death toll hits 21 (Reuters)
from the article: Palestinian activists urge Hamas to probe own Gaza war crimes