Two rounds struck the sprawling embassy compound but it was not immediately clear which part of the complex, and a U.S. Embassy official said the incident was under investigation.
"At approximately 6:40 local time in Kabul, approximately two rounds of indirect fire impacted the U.S. Embassy compound," said the official, who spoke on condition of anonymity in line with regulations. "All Americans are accounted for and no injuries were sustained."
Indirect fire can refer to either mortars or rockets.
The Taliban promptly claimed they fired four rockets at the American Embassy on Wednesday and said they inflicted heavy casualties. But the insurgents often exaggerate their claims.
Elsewhere, an Afghan official said a bicycle bomb was remotely detonated in front of a restaurant at a bazaar in Puli Alam, the capital of Logar province, 60 kilometers (37 miles) east of Kabul, killing six people and wounding 13.
Two of the killed were policemen and four were civilians, said Abdul Wali Tofan, the deputy police chief in Logar province. He said the attack also wounded 13 civilians, including several children.
Earlier in the day, a roadside bombing in eastern Kabul wounded three Afghan policemen. Kabul police chief, Mohammad Zahir, said one suspect was arrested over that attack.
Police later uncovered an unexploded bomb in the same area and successfully neutralized it, Zahri said.
Afghan insurgents have increased attacks in recent months, intensifying a campaign to regain territory as foreign forces draw down ahead of full withdrawal at the end of 2014.