I've answered it many times. You just don't like the answer.
Israel, USA and UK designate Hamas as a terrorist organistion.
The UN do not designate Hamas as a terrorist organisation.
Designation of an organisation is a political ploy to justify the treatment of your adversary.
I refer you to my recent comment on the Mau mau being designated as a terrorist organsation, and my previous comments on the IRA, etc.
Also Zionist organisations were designated as terrorists. Israel politics is now dominated by Zionists.