The European football's governing body confirmed the decision on Wednesday.
City were punished by UEFA's disciplinary committee for returning late to the field following half-time in the March 8 match at the Jose Alvalade stadium, which Sporting won 1-0.
A UEFA spokesman confirmed they had informed City of the punishment on Wednesday and that the Barclays Premier League side had three days to appeal against the fine.
The punishment comes a week after another Portuguese club, Porto, were fined £16,700 by UEFA for their fans' racial abuse of City players in the same competition in February.
City pair Mario Balotelli and Yaya Toure were both subjected to monkey taunts during a last-32 game at the Estadio do Dragao, prompting a complaint from the English club.
City went on to beat Porto 6-1 on aggregate to set up the tie with Lisbon.
They were beaten by a goal from Brazilian Xandao in the Portuguese capital on March 8 before being knocked out on away goals after a 3-2 win at the Etihad Stadium the following week.