Hernandez was forced off due to injury in the second half of United's fifth straight win of the season after being on the wrong end of what Ferguson felt was a "shocking tackle" from the England full-back.
It is not known how long the Mexican will be sidelined for.
However, Hernandez was in obvious pain as he hobbled down the tunnel and Ferguson was not impressed.
"It was a shocking tackle," he told MUTV.
"The referee booked him, so I don't understand why he hasn't given a penalty.
"Ashley Cole is very reckless at times. He is committed of course but being committed you can sometimes go over the edge a bit.
"That was an example of that."