Television pictures showed a number of travelling Rangers fans clashing with Romanian police in the stands while one supporter was seen to rip out a seat during the trouble.
Police used CS gas spray in an effort to disperse Gers fans during what Rangers Supporters Assembly chief Andy Kerr described as a "minor incident".
Rangers chief executive Martin Bain is expected to tell UEFA that he believes poor organisation and over-zealous policing contributed to the trouble, but UEFA's director of communications Rob Faulkner admitted the reason for the clashes requires further investigation.
"As far as we can establish at the moment it seems there were a number of Rangers supporters who came late into the stadium, and we need to find out why," Faulkner told Sky Sports News.
"Then there was an issue about where they were going to sit as apparently there were banners already placed there, which resulted in the request to remove some banners, which seems to have ended in a clash between stewards and some supporters.
"We'll wait until we get all the facts in from our official reports and we'll study those before we decide what to do."
Rangers chief Bain condemned the "unacceptable" behaviour of some of the Glasgow club's travelling fans in Bucharest, but was also critical of the shortage of entry access for spectators at the Steaua Stadium.
He claimed a promise that four turnstiles would be open for visiting fans was not kept, causing problems which were compounded, he claimed, by police using CS gas.
When questioned over Bain's concerns over turnstile access, Faulkner said: "If that's the case, definitely [we will look at it]. If that's what had been agreed beforehand. again we'll have this in the reports.
"If that is the case it will be taken into account should we move into any kind of disciplinary case."
He added: "We should get the reports in during the course of today, and then we'll look at those.
"If we need to discuss with people who were there on site we will do that, and obviously we'll take action after that. In the next couple of days we should know."