+0

The management has instructed us not to carry out any personal work last week

The management has warned us not to do any personal work last week.

+0

Unless it was sent out as a threat, I would use 'instructed' or 'told'. However, do you mean LAST week? Is that the time when you were told this, in which case I'd put this information at the start, or have you been told not to carry out personal work NEXT week?

E.g.

Last week, the management instructed us not to carry out any personal work.

The management told us not to do any personal work next week.

Comments  
Teachers: We supply a list of EFL job vacancies

Thank you,

I meant. last week, we were informed by the management regarding the personal work.

anonymouslast week, we were informed by the management regarding the personal work.

I think this is what you meant:

Last week, management informed us that we must not do any personal business during work hours. 

Personal business = making doctor's appointments, arranging to pay a bill, studying for an entrance exam, selling stuff on ebay and the like.