The defender was charged with a level one offence against the Eagles' Matt Rosa during the second quarter of Friday night's match.
His early plea resulted in 60 demerit points being added to his future record.
The sanction details were as follows:
Scott Thompson, North Melbourne, has accepted a reprimand and 60 points towards his future record for striking Matt Rosa, West Coast, during the second quarter of the Round Eight match between North Melbourne and West Coast, played at Patersons Stadium on Friday May 17, 2013.
