The Portuguese star's frustrations got the better of him as he trudged off the Goodison Park pitch following a humiliating 1-0 defeat to Everton on April 22.
The veteran striker was recorded launching a young Toffees fan's phone to the floor as he was receiving abuse from supporters.
Merseyside Police have investigated the incident, cautioning the Manchester United striker.
A statement on Wednesday, August 17 reads:
“We can confirm that a 37-year-old man voluntarily attended and was interviewed under caution in relation to an allegation of assault and criminal damage."
"The allegation relates to an incident following the Everton v Manchester United football match at Goodison Park on Saturday 9 April. The matter has been dealt with by way of conditional caution. The matter has now concluded."
The report adds that it is believed Cristiano Ronaldo has agreed to pay compensation for the incident.
The teenager's mother described the player as being in a "terrible, terrible temper" before he "smashed the phone" to the floor.
The Red Devils star apologized following the incident on Instagram, inviting the teen boy watch a game at Old Trafford, The invitation was declined.
The FA are now set to open their own investigation on the matter following the Police cautioning the five-time Ballon d'Or winner.
Cristiano Ronaldo's future still up in air
There is still a ton of uncertainty over the future of Cristiano Ronaldo with the Portuguese ace still seeming to desire leaving Manchester United.
He was part of the side that endured an embarrassing 4-0 defeat to Brentford on August 13.
His frustrations following the thrashing were bordering on the same level as those shown against Everton last season.
He was recorded storming off the pitch in fury following the defeat, rejecting assistant manager Steve McClaren's advice to go over to the club's supporters.
Reports claim that the five-time UEFA Champions League winner wants to continue playing in that competition.
Ronaldo rejoined Manchester United from Juventus last summer and impressed for the Red Devils in his first season back.
He managed 24 goals in 38 appearances but United finished sixth in the league, meaning that they will play UEFA Europa League football.
The veteran striker has one year left to run on his current deal at Old Trafford, with the option to extend for a further year.
Ronaldo has promised to reveal the truth about his situation in the coming weeks.