In a statement late Saturday, the embassy said it will be "closed for routine services" Sunday "as a temporary precautionary measure."
The unusual decision comes after four Americans - two soldiers and two contractors - were killed in a suicide attack Saturday on the Bagram Airfield near the capital, Kabul, the Associated Press reported.
Two days earlier, insurgents attacked the German Consulate in the northern city of Mazar-i-Sharif, killing six people and wounding more than 100.
The US Embassy in Kabul regularly warns Americans against travel to Afghanistan, where a Taliban-led insurgency is in its 16th year.
The insurgency has become more virulent since 2014.