The junior tennis player who slapped his opponent in the face following a match earlier this week has issued an apology ... saying his actions were "wrong and completely out of line."
Just three days after 15-year-old Michael Kouame smacked 16-year-old Raphael Nii Ankrah following a loss at an ITF juniors tournament in Ghana ... he said he was very sorry.
Kouame -- who posted the mea culpa on his social media page -- said he acted out and slapped Ankrah after hearing heckling from the crowd during the match.
"I was repeatedly verbally abused by a large number of individuals in the crowd, including insults to my mother in particular," Kouame said. "However, that does not excuse my behavior."
Kouame directly apologized to Ankrah ... and said he'd take any punishment that officials inevitably hand down.
"[I] will use this time to reflect on how I can better manage challenging situations like these in the future in a manner that accurately reflects my character," Kouame said.
The teenager had come into the tournament this week as the No. 1 seed.