What is the most difficult part about managing a team?

Making the team accountable for the performance! Training and coaching to enhance their productivity.

Dealing with each one's different attitude and personality

Dear Roba, I believe the difficult part in managing a team would be to create such a conducive environment where each of the member can contribute to their maximum potential as an individual and keep their differences aside for the common goal.
Regards Tahir

Tounderstand each Team member behavior which will take a lot of efforts amended to be inline with the code of conduct.

Creating and maintaining team spirit between the members.

la qualité de la formation des agents et le manque d'informations

Listening and Understanding.

To listen and understand well enable us to achive correctly and on time.

employees with bad attitude

I would suggest "Building team members trust on you".
Once you will get trust of your team then you can motivate them towards goals and even can resolve their issues and maintain spirit between them.

Striking the balance of rewards between unequals