The fly-half was involved in a couple of scuffles with French players during England's 23-13 victory at Twickenham last weekend before being substituted with a leg injury, but Lancaster insists that he has no concerns over the 21-year-old's temperament.
"We could micro analyse every individual's body language and everything they do in every game. The reality is I thought he had a good game and was frustrated to come off injured," Lancaster said.
"With all players it's about hitting the balance between being on the edge and in control, over the edge and out of control or not quite at the edge and getting blown away by a side that is hugely motivated.
"In the review of course we talked about discipline, but there were other things that were equally important."
Farrell's injury will keep him out of action for a further week.