You should know that Israelis mourn Gazan casualties as well. We hate the Hamas, but certainly not the people of Gaza.
Many Israelis don't even if you do, and you certainly don't respond to suffering on both sides in the same way. As a Brit I know the rocket attacks the Israelis are coming under are terrible compared to my cosey little existence, but they're almost comical compared to the suffering of the Palestinians: Hundreds of dead, thousands of injured, hundreds of thousands forced to flee their homes and over a million without basic utilities, struggling to find food and water.
People wonder why so many Palestinians support Hamas when they 'bring these attacks upon the Palestinian people' but they're missing the point. The existence of the French resistance during WW2 led to thousands of the French suffering in response, but they considered the resistance as the only way to fight back against an oppressor. In Palestine the Israelies are seen as that oppressor, and even if the resistance is largely ineffective and leads to reprisals, they will be supported because people support those they see as fighting for them against an oppressor.
Israelis constantly make the point that Hamas targets civilians when they don't. Firstly, given the vastly larger number of Palestinian civilians killed it's a pretty arbitrary point and secondly Israel can effectively strike at Palestinian military organisations with minimal risk, how exactly do you suggest that Hamas fights a conventional war agains the IDF? Lastly, look back at the post WW2 period and the founding of Israel and the acts of terrorism, including many targetting civilians, by Jews at the time. Back when your country didn't have overwhelming military power your ancestors were perfectly happy to use terrorism to achieve its goals; which makes this protest agains the same methods 60 years later look more than a little hypocritical.