"We recognise that TV Novosti [RT], providing a service with a Russian background, will want to present the news from a Russian perspective. However, all news must be presented with due impartiality," the body said in a bulletin report.
Ofcom argued that RT did not reflect the stance of the Ukrainian government while covering the post-coup events in the country in early March.
"We therefore considered that TV Novosti should have sought to reflect adequately the viewpoint of the interim Ukrainian Government in response on the significant allegations in this news item that it supported extremist views," the report said.
The regulator found that the TV news channel violated several points of its broadcasting code, adding that future breaches may result in "further regulatory action, including consideration of a statutory sanction."
RT Editor-in-Chief Margarita Simonyan told Sputnik Monday that the channel respected Ofcom's stance and expected the high broadcasting standards it promotes to be applied equally to all media operating in the United Kingdom.
"The media subject to UK jurisdiction by no means always reflect the governments' viewpoints, if they [the viewpoints] do not politically match the view of European or US political circles," she added.
Simonyan added that international media experts had praised RT's coverage of the Ukrainian crisis, for which the channel received a nomination at the 2014 Monte Carlo Television Festival.
RT is a Moscow-based international TV network, broadcasting in English, Spanish and Arabic in over 100 countries worldwide. The network also includes RT America and RT UK news channels, broadcasting from studios in Washington and London.