The player claimed he was nearly hit with a "lighter or whistle" thrown from the East Stand at Fir Park during Hibernian's 3-1 victory on Saturday.
Referee Steve Conroy picked up the object and it is understood the incident has been included in SPL match delegate Gerry Collins' report.
A spokesman said: "If there are any crowd incidents reported to us, the first step is to write to both clubs involved and seek any information that may be relevant. What we're looking for is to make sure the clubs took the right action with regards to ticketing, crowd operation and stewarding, and reacted to the situation in the right manner. Clubs can't control every single supporter but we look to see whether the club reacted correctly to any situation."
A Motherwell spokesman said: "We have launched an internal probe and appeal to supporters with any information over the incident to contact us. Anyone found guilty of throwing a missile would face appropriate action. The club qualified for Europe this season through the Fair Play League, part of which was judged on our supporters' behaviour. So, although it is disappointing, we believe this was an isolated incident."