Unidentified gunmen on Saturday, fired shots at Bilawal House, the residence of Pakistan People's Party co-chairman Asif Ali Zardari, though no one was injured in the incident.
Sources in Bilawal House said five car-borne assailants fired six shots at the main gate of the residence in the posh Clifton area of the port city.
The gunmen fled when security guards returned fire.
Sindh Chief Minister Qaim Ali Shah and provincial police chief Shoaib Suddle visited the place, named after Zardari's son and PPP chairman Bilawal Bhutto Zardari, soon after the incident to assess the situation.
Police recovered empty cartridges near the gate and registered an FIR against the unidentified attackers.
Police also set up a new check post in Clifton and increased the deployment at Bilawal House.
Senior PPP leader Faisal Abidi appealed to party workers to remain calm as "some forces" wanted to spoil the peace in Karachi.