"US citizens should not travel to Russia, and those who live or are in Russia should leave Russia immediately while there are limited opportunities for commercial travel," the embassy said in a statement.
There are fears that Russian authorities may not recognize Russian-US dual citizenship and deny people with such documents access to US consular assistance, prevent them from leaving Russia and draft them into military service.
"We remind US citizens that the right to peaceful assembly and freedom of speech is not guaranteed in Russia. Avoid any political or social protest, and do not photograph law enforcement officers at these events. The Russian authorities have arrested US citizens who participated in the demonstrations," the embassy warned.
Earlier, Bulgaria, Poland, and Estonia authorities issued a call to leave Russia and not go there.