Does Razing cities hurt your rep or attitude of other civs towards you?
It hurts their attitude toward you, but has no effect on your rep.
I've been doing honorable wars, but i raze all cities i capture.
But then, everybody hated me, why was that?
Razing affects their attitude.
Then everybody started declaring war at me. >.<
That could be caused by several things. You didn't say what year it is. In the early game, other civs declare if they think your military is weak, and some of the more agressive tribes like the Germans, Zulus, Aztecs just seem to enjoy fighting.

Also, you may have a resource the other civs want.
In the later game, keep an eye on your F4 screen (and be sure you have embassies so you can see the AI relationships). If they have MPPs with each other, you can end up being declared on by another civ if you attack just one of the partners to the MPP.
In any era of the game, if you attack another civ, they may buy other civs into a Military Alliance against you. Sometimes you can prevent this by allying another civ first to help you before your enemy can ally with them.
Lastly, if you are very close to victory of any sort, it appears to draw attacks from other civs just to prevent you from winning. This isn't in any official game rule that I know of, but it just seems that way to me. I'll be attacked a few turns before I complete a space ship or before I achieve a cultural win.