Dandjinou said he does not rule out the deadly shooting attack was a terror act.
"In the current situation, we cannot exclude a terror attack," Dandjinou said as quoted by RFI Afrique broadcaster.
The incident took place at around 09:00 p.m. local time (21:00 GMT) when three assailants on a vehicle perpetrated a shooting attack on the cafe visitors which subsequently lead to a fire-fight with the security forces.
The security operation was underway in the cafe area late at night on Sunday, the reports added. The security forces, which have cordoned off the area, said that the threat was confined to it and urged the public to avoid the quarter, the broadcaster added.