The Independent Manchester United Supporters Association (IMUSA) reacted angrily to the FA's decision as they have repeatedly failed to consult supporters.
IMUSA chair Mark Longden said: "It's ridiculous.
"I think the real issue here is why the supporters were not consulted. If
"It seems that every year we have these issues over venue and allocation, but no-one ever asks the supporters what they think."
An FA spokesman said: "The difference between the allocations is a total of 200 tickets, and we have to divide the stadium somehow.
"If you incorporate the hospitality areas, there will actually be more Manchester United fans inside the ground.
"The United allocation was also reduced on the basis of advice from Aston Villa's safety officer, due to the fact that they persistently stand when they go to