Vladimir Putin would honestly prefer to see the issues between the US and Iran resolved diplomatically. Russia and Iran are allies. Putin does not want to see a war break out between the US and Iran that could drag Russia in.
That being said, the Russians have made it clear to the Iranians that in the event of American air strikes, Russia will fully support Iran in exercising its right to defend itself.
Iran has invested heavily in the past 20 years in precision-guided, ballistic missiles that are specifically designed to knock out the US’s airbases guarding the Persian Gulf.