The US Embassy in Russia issued an urgent warning of an “imminent” terrorist attack in Moscow — just hours after ISIS was thwarted from a planned massacre at a synagogue.

“The Embassy is monitoring reports that extremists have imminent plans to target large gatherings in Moscow, to include concerts, and US citizens should be advised to avoid large gatherings over the next 48 hours,” the embassy said on its website.

American citizens — already warned off being in Russia during its war on Ukraine — were specifically told to “avoid crowds” and “be aware of your surroundings.”

The warning came after Russia’s FSB security service said an ISIS cell operating in Russia’s Kaluga region — as part of the Afghan arm, known as ISIS-Khorasan — was plotting to massacre Jewish worshippers at a synagogue in Moscow.

The cell “was preparing to attack the congregants of a synagogue using firearms,” the security service said.

When Russian special forces raided the ISIS cell’s headquarters, the militants put up a fight and were “neutralized,” according to the FSB.

“Firearms, ammunition, as well as components for the manufacture of an improvised explosive device were found and seized,” the agency said.

With Post wires