PA:
The French side have also received a £42,000 penalty for a range of offences.
The match at the Stade Felix-Bollaert in Lens was disrupted when United fans became crushed into a section of the ground and police responded by firing tear gas.
Lille have been fined by UEFA for breach of security provisions and a lack of proper organisation, and also for the reaction of their players after Ryan Giggs' winning goal in the first leg.
The French team threatened to walk off the pitch after the goal, which came from a quickly-taken free-kick.
UEFA's control and disciplinary body imposed the fine on United after some fans let off fireworks, and others were involved in disturbances at the entrance to the stadium.
A statement from UEFA said: "The French club were fined 100,000 Swiss francs for breaches of security provisions and lack of proper organisation, as well as for the improper conduct of the team after United's goal in the English side's 1-0 victory.
"The penalty was handed down by the UEFA control and disciplinary body after an examination of the match officials' report and the report by the UEFA disciplinary inspector, written evidence of the parties, an examination of the video surveillance pictures in the stadium, and examination of video images of the match.
"Manchester United have been fined 15,000 Swiss francs for the improper conduct of their fans at the game, which included the setting-off of fireworks and disturbances at the entrance to the stadium.
"Appeals may be lodged against the verdicts within three days of receipt of the written grounds for the decisions."
United believe a tragedy was only narrowly averted after supporters became crushed into a section of the Stade Felix-Bollaert but the head of security at the stadium had accused United fans of sparking the problems with "violent behaviour".
Lens' stadium security chief Damien Vanoise said the day after the game: "There was not a problem of communication. From the moment we saw the supporters trying to pull on the railings, what interpretation we can make of that, as security guards? For me, it was violent behaviour.
"I can tell you that nobody was crushed in the wire fencing.
"There weren't too many people in that stand. The stand was not full."
United strongly denied the claims.