Award-winning REN TV presenter Tatiana Limanova allegedly made the gesture while reading Obama's name during a Nov 14 news item on the Asia Pacific Economic Cooperation (APEC) conference. Online footage of the incident has since gone viral.
REN TV, however, said Limanova's gesture was not aimed at Obama, but was rather a response to her "editorial staff" colleagues, who were standing off camera and trying to distract her, for a joke.
It was not, REN TV stressed in a statement, "linked to the item being presented by Limanova".
Limanova said she did not know she was on camera when she made the gesture, an explanation that failed to impress the REN TV bosses.
"This does not diminish her guilt and cannot be considered an excuse. The REN TV management views this action as the gravest violation of on-air discipline and a demonstration of unprofessionalism," the channel said.
Limanova is not the only Russian newsreader to have made the headlines for similar reasons.
Irada Zeinalova of the state-run Channel One TV channel has sworn at least twice on camera. In one such incident, her anger was directed at a small boy who accidentally distracted her while she was recording a standup.