The attack took place around midnight on Wednesday, reports Xinhua news agency.
"Immediately before the suicide, the person threw an explosive device into the compound of the embassy from an intersection near the sports centre in Podgorica," the police said.
It added that the explosive device was most likely a hand grenade. Identification of the assailant was underway.
The US State Department said that the embassy has been conducting an internal review to confirm the safety of all staff, according to spokesperson Heather Nauert.
The embassy has warned American citizens of "an active security situation at the embassy" and to avoid the embassy "until further notice".
Located in southeastern Europe, Montenegro has a coast on the Adriatic Sea to the southwest and borders Croatia, Bosnia and Herzegovina, as well as Albania.
The Balkan country declared independence in June 2006, after it separated itself from the Federal Republic of Yugoslavia, a federation it established with Serbia in 1992.
Last May, Montenegro joined the North Atlantic Treaty Organisation (NATO), leading to large protests by the pro-Russian opposition and anti-NATO demonstrators.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
