A number of Premier League clubs cut the allocation of tickets for United fans last season because they claim fans block the isles, stand up and abuse stewards.
United fans will be half in numbers to what usually cheer on the team at Anfield, just over 1,900 will be allowed in this time.
This prompted Ferguson to write to fans.
"Despite intense lobbying by the club on your behalf, there will only be just over 1,900 United fans at Anfield," The Reds boss wrote.
"We can't allow this situation to continue. I've said many times that your support is a vital part of our success and, trust me, the players do notice when your numbers are cut."