Four people were wounded when gunmen attacked the Omani embassy in the Iraqi capital, Baghdad, police say.
At least one embassy worker and two Iraqi guards were hit in the drive-by shooting in Mansour district shortly after 1800 (1500 GMT), they say.
The attack came hours after US Secretary of State Condoleezza Rice called on Arab nations to re-open embassies in Iraq.
A driver for Sudan's embassy was killed in the same district on Thursday.
Police immediately sealed off the area of Friday's shooting.
Over the past few months, al-Qaeda in Iraq - led by Abu Musab al-Zarqawi - has said it was behind the killing of an Egyptian envoy to Iraq, along with the abduction and killing of two Algerian diplomats.
The group said it acted to encourage Muslim countries to sever ties with the US-backed Iraqi government.