Foreign Minister Manuchehr Mottaki made the announcement but did not give any further details.
Eight people were killed and 46 were wounded in the blasts, in an oil-rich area in southwestern Iran populated by ethnic Arabs.
Ten people were arrested in connection with the bombings.
The regime immediately blamed Britain for involvement in the explosions. Britain denied that accusation as being completely without foundation.
Iran's Arab Minority
The aftermath of a car bombing in Ahvaz on June 12, 2005 (epa)
DISCONTENT IN THE SOUTH: There are approximately 2.07 million ethnic Arabs in Iran (3 percent of the total population of 69 million), most of them living in the region around the southern city of Ahvaz. The region has been the scene of numerous terrorist attacks and demonstrations over the years. Arab groups cite historical grievances, and they bemoan inadequate attention to their culture and language by state media....(more)