Neto pushed a ball-boy off his chair in the closing stages of Chelsea's 5-2 defeat in the first leg of their last-16 tie at Parc des Princes on Wednesday, as he tried to retrieve the ball, sparking a melee between players from both sides.
Neto, who later apologised profusely to the youngster, could receive a suspension for the second leg, with other potential sanctions including a fine or simply a warning.
A UEFA statement read: "Disciplinary proceedings have been instigated against Chelsea player Pedro Lomba Neto for unsporting behaviour in accordance with Article 15(1)(a)(v) of UEFA Disciplinary Regulations.
"UEFA's disciplinary bodies will take a decision on this case in due course."
Neto revealed he had apologised to the ball-boy after the game in a post-match interview on TNT Sports.
He said: "I'm not like this. It was in the heat of the moment and I want to apologise. I gave him my shirt. I'm really sorry about it - I feel I have to apologise to him.
"My French is not very good, and Vitinha came over and said to him I was not like this.
"At the end the ball boy laughed and I gave him my shirt and said sorry about 35 times. He could see what had happened and was happy with the situation."
Chelsea will bid to overhaul their three-goal disadvantage against PSG in the second leg at Stamford Bridge next Tuesday.
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