The explosive device, fitted with a timer, was placed outside the restaurant in Quetta, local police chief Mir Zubair Mehmood said.
It was timed to explode late in the night when people had gathered on the eve of Independence Day being observed on Tuesday, he said.
"At least 12 people were injured, one of them is in serious condition," Mehmood told AFP.
He blamed militants, saying "they wanted to create panic to disturb the national day celebrations".
There was no claim of responsibility for the latest incident but the province which borders Iran and Afghanistan suffers from Taliban attacks.
It is also a flashpoint for sectarian violence involving Sunni and Shia Muslims that has left thousands of people dead since the late 1980s.
Bomb blasts and attacks on police and security forces are frequent in insurgency-plagued Balochistan.
COMMENTS (4)
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ
@Salman mirza:
The slaves of Foreigners claim that they are giving independence to the independent sovereign people of Balochistan. What a farse.. The leaders of your movement are themselves begging for food from UK, Switzerland and UAE. They donot have the capacity to earn square meals with honour for them selves. We look down upon these people and consider them nothing more than spies of enemies..
@Baloch: We the people of Balochistan condenm the coward attack. We stand with Pakistan and will work for its development and peace in the area.
My whole support for Baloch freedom. Days of oppression torture killing should come to an end with the rise of free Balochistan.
Azaad Balochistan This is a warning for Pakistanis to refrain from celebrating your independence day in our beloved Balochistan