Celtic have written to the Scottish Football Association about the refereeing of their Scottish Cup semi-final defeat by Inverness CT.
The Parkhead side were angered by referee Steven McLean's failure to award a penalty for handball against Josh Meekings when they led 1-0.
Caley Thistle won 3-2 in extra time.
"Given the level of reaction from our supporters and across football, we are duty bound to seek an understanding of what actually happened," the club said.
"We have not been given any other specific explanation so far and this is simply to understand the circumstances of what went on and why such an obvious error was made."
Celtic congratulated their opponents, describing Caley as "a fantastic club" and saying "reaching the final is a great achievement".
The Scottish champions took the lead through a Virgil van Dijk free-kick, but were denied a first-half penalty when Griffiths' header hit the arm of Meekings.
Ronny Deila's men had goalkeeper Craig Gordon sent off in the second half for bringing down Marley Watkins in the box, with Greg Tansey scoring the subsequent penalty.
Edward Ofere put Caley Thistle ahead but John Guidetti levelled before David Raven's extra-time winner.