"Serious companies will hardly be guided by such ratings which do not reflect a real state of affairs." - Dmitry Peskov, RIA Novosti
"The fact that this step has been taken now is not surprising: by strange coincidence it came during a fresh spike in anti-Russian hysteria," Nebenzya added.
President Vladimir Putin's spokesman also said the rating downgrade was politically motivated.
"Serious companies will hardly be guided by such ratings which do not reflect a real state of affairs," Dmitry Peskov was quoted as saying by RIA Novosti.
Standard and Poor's became the first major international ratings agency to move Russia down into speculative or "junk" territory, the first such downgrade for the country in a decade.
The cut piles further pressure on Russia's beleaguered economy which is already reeling from low oil prices and several rounds of Western sanctions.
Copyright Agence France-Presse, 2015