At least two people were injured after political workers belonging to the Pakistan People's Party (PPP) and Imran Khan's Pakistan Tehreek-e-Insaf (PTI) clashed early on Tuesday, in Pakistan's southern city of Karachi, local media reported.
The incidents came in the wake of an assassination attempt on a minister which has deepened divisions ahead of Pakistan's elections.
A gunman shot interior minister Ahsan Iqbal, a senior member of the ruling Pakistan Muslim League-Nawaz (PML-N), heightening a sense of unease in the run-up to the general election, expected by late July.
The clashes ended after heavy security arrived at the scene.
The minister for Sindh province, of which Karachi is the capital, Sohail Anwer Siyal said the government was investigating the incident.