Both players gave solid performances during England's nail-biting 10-run victory over Sri Lanka in New Delhi to secure a place in the semi-finals.
But Roy was fined 30 per cent of his match fee for swearing and then throwing his bat and helmet upon leaving the field, after being given out lbw for 42 off 39 balls.
England in semis, dump Sri Lanka out of World T20
The International Cricket Council (ICC) said on Sunday that Roy had shown "dissent at an umpire's decision during an international match".
Willey, meanwhile, who took 2-26, was fined 15 per cent of his fee after giving a colourful send-off to Milinda Siriwardana when the Sri Lankan was dismissed immediately after hitting the seamer for six.
The ICC said he breached the code of conduct for "actions or gestures which disparage or which could provoke an aggressive reaction" from a batsman on their dismissal.
Mathews urges patience after Sri Lanka World T20 exit
Both players admitted the offences during a meeting with match referee Jeff Crowe, the ICC said in a statement.
England are now likely to face New Zealand in a semi-final encounter in Delhi on Wednesday, with the West Indies having already qualified from their group.
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