The Red Devils manager did not allude to the race row between the two clubs in his letter, but simply requested that the United following 'respect' Liverpool's stadium in order to secure future allocations at Anfield.
"Please do everything you can to continue that good work and protecting next season's allocation by going to the seat that you've bought, not blocking aisles and gangways, respecting the stewards and following the ground regulations," Ferguson wrote.
"FA Cup ties are tense affairs at the best of times. Add in the fact that Manchester United against Liverpool is the biggest game around and it becomes even more so.
"Your support is vital to the team and down the years that has been especially true at Anfield. But please put the emphasis on getting us into the next round and giving the sort of support you are famous for - positive, witty and loud."
Suarez will not feature in Kenny Dalglish's side as he continues to sit out an eight-match ban served to him by the Football Association.