Is it necessary to have a work experience for MBA to get admission in Germany? Or some universities demands it and some not.

Fresher's MBA they will not ask experience. Executive MBA requires two or three years experience. AMBA MBA you need three years managerial experience. AMBA. is the best one details see in www.amba.com

almost all top world best university ask for experience of minimum 2 years for mba

Soleley depends on the colleges. Some do require it but majority of them do not. You need to have gud Statement of Purpose and Letter of Intent and good entrance exam score.