Staff at the chain Johnny & Jugnu in Lahore were rounded up at 0100 (2000 GMT) on Saturday and held overnight.
"This is not the first time something like this has happened... at our restaurant," a statement by the burger chain said.
Nine police officers involved in the incident have now been suspended.
Senior provincial police official Inam Ghani announced the suspensions on Twitter, saying: "No one is allowed to take the law into his own hands. Injustice will not be tolerated. All of them will be punished."