Ghanaian Gyan was sent off with 20 minutes remaining for a lunging scissor tackle on the skilful Salem Al-Dawsari as the Emirati side were knocked out 4-2 on aggregate despite winning Tuesday's home match 2-1.
Pintilii ran over to Gyan to remonstrate after the tackle near the left hand touchline, which sparked a melee between a number of players from both sides.
Ghana captain Gyan, the tournament's top scorer with 12 goals in as many games, posted a message on his Twitter account on Wednesday saying "it happened" with a link to an article claiming the player was subjected to "racist abuse".
"The player has no right to tell me what he did," Gyan said.
"He said something to me which made me upset. He said an abusive word -- I really didn't like it. He knows what he said, you can ask him. He knows what he said,” he added.
The article added that Al Ain were expected to launch a formal complaint to the Asian Football Confederation upon gathering all details about the case.
Gyan, who joined the club originally on loan in 2011 before making the deal permanent a year later, was involved in some pushing and shoving before leaving the field following the dismissal which came with the scores level on the night at 1-1.
The 28-year-old said he deserved the red card after mowing down the winger.
"I must confess it was a harsh tackle. But in my mind I did not go for the player, I just went in strong for the ball," Gyan said.

"I am a professional. The referee took his decision. It is football so I cannot complain. I lost my head a bit, but life goes on,” he added.
Al Hilal will face the winners of Wednesday's second semi-final between Western Sydney Wanderers and FC Seoul which is level after a goalless first leg draw in South Korea.

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