"We recommend that you exercise caution, especially in the vicinity of large gatherings, utilize good situational awareness and monitor local media for updates," the US embassy said in three separate alerts.
Several hundred people plan to participate in the rallies, which have been organized by different political and civil society groups, the embassy said.
After the US, the UK and France launched missile strikes on a number of targets in Syria on Saturday morning in response to an alleged chemical weapons attack in Douma, in Eastern Ghouta, multiple rallies were held in the United States and Britain, protesting the attack.
While Western states have been blaming the Syrian government forces for the incident, Damascus has denied using chemical weapons.
According to the Russian Defense Ministry, Damascus didn't use chemical weapons in Douma, while Moscow has evidence confirming the incident had been staged by foreign security services and militants based in the city.