"This, of course, is the height of fakery," foreign ministry spokeswoman Maria Zakharova said.
Zakharova posted a video of Lavrov, President Vladimir Putin's foreign minister since 2004, sitting outdoors on a patio, dressed in shorts and a T-shirt and reading documents.
Asked about the report, Lavrov said Western journalists had been writing falsely for a decade that Putin, 70, was ill.
"This is a kind of game that is not new in politics," Lavrov said with an ironic smile. "Western journalists need to be more truthful - they need to write the truth."
Lavrov said Western media routinely took a partial view of events and ignored Russia's point of view.
Bali Governor I Wayan Koster told Reuters that Lavrov had breifly visited Sanglah Hospital in Bali for a "check-up" but that the minister was in good health.
"He was in good health and after the check-up he immediately left," the governor said.