Premier League - Rooney to learn fate on Monday
Rooney has apologised for shouting an expletive into a camera after completing a 14-minute treble that inspired his team to come from two goals down to beat West Ham United 4-2 and go seven points clear at the top of the Premier League.
"Tomorrow there will be a decision," FA director of football development Trevor Brooking told BBC Radio 5 Live on Sunday when asked whether the governing body would be investigating Rooney's outburst.
"It was a surprise, having scored a hat-trick, to react that way. It is something we will have to look at."
United published a statement from Rooney on their website on Saturday.
"I want to apologise for any offence that may have been caused by my goal celebration, especially any parents or children that were watching," the 25-year-old said.
"Emotions were running high, and on reflection my heat-of-the-moment reaction was inappropriate. It was not aimed at anyone in particular."
Rooney had been mobbed by team mates as he celebrated his first hat-trick of what has been a troubled and below-par season before heading towards a television camera and yelling into it.
His behaviour, rather than his three goals, dominated the back pages in British newspapers with The Sunday Times' main headline announcing "Red Devil Turns Air Blue" and The News of the World declaring "Rood Yob".
Rooney made headlines at last year's World Cup for another television outburst when he turned to a camera and shouted "Nice to see your home fans boo you. That's what loyal support is," after jeers greeted England's abject 0-0 draw with Algeria.
His season has been hit by injuries, off-field problems and a loss of form and Saturday's goals took his league tally to 10.