Police also fired water cannon to disperse the party activists, who reportedly indulged in stone pelting, from Metropole in Karachi.
The incident has reportedly left six people injured.
The PTI activists were protesting against the refusal of sugar mills to pay the officially fixed price of cane crop to farmers.
The police also detained 12 protesters including PTI senior leader Arif Alvi, who was later released, The Express Tribune reported.
Earlier in the day, the PTI organized its Kisan Insaf Rally from Hyderabad, where the protesters announced their plan to stage a sit-in outside Sindh chief minister's house against the sugar mill owners.
Meanwhile, PTI chief Imran Khan condemned the use of force against the protesters and said his party stood with the famers who should get the right price from the powerful sugar mills' owners.
"Shameful how Sindh govt used force in Karachi on a peaceful protest by sugar cane growers against the grave injustice being done to them by the sugar mills. We stand with the hard working farmers who should get the right price from the powerful sugar mills' owners cartel," Khan said on twitter. (ANI)