Asperger in the Kindergarte - What can we do

Our 5 years old son has been diagnose Asperger. Even though we do not desagree completely with this diagnostic, he seems to be a very light one. The main problem we think is affecting him is understanding social unspoken rules. Specially in the Kindergarten we get a lot of complains from the teacher because he needs a lot of attention to complete the classroom written assigments. When we ask him what is happening, he mentioned that he was dissapointed with one of his classmates because he did not want to be his friend (or similar situation). Apparently these social problems are affecting him a lot because the teacher said that is very difficult to get him concentrated in the classroom tasks. Sometimes he gets violent (bit or hit) with his classmates if he feels they are not accepting him or his ideas.
Does anybody had had similar situation? What do you think would be a good way to address this problem?
Thank you for your help!!!

My sons was also diagnosed with Aspergers, he is Kg, andf it's very frustrating, he tends to have a problem with large groups, and almost everything that you said plus more,and now we are considering sending him to a different school, that fully meets his needs.Have you considered that?