Arsenal have been fined 40,000 for failing to control their players conducted during the 3-0 FA Cup win over Oxford United on 12 January.
It relates to an incident in the 34th minute of the third-round tie, when some Arsenal players protested to referee David Coote after they were denied a penalty for a handball against United's Elliott Moore.
The Gunners denied the allegations and requested a hearing, but an independent Regulatory Commission has upheld the allegation.
An FA spokesperson said the commission's "written reasons for these decisions will be published in due course".