Addressing a press conference in Lahore, Hafiz Naeem said the party's campaign was progressing successfully and demanded that the federal government reduce petroleum prices.
He said the protests would continue until the government implemented the party's demands rather than merely providing assurances.
"The sit-in will end only when the government implements our demands in practical terms," he said.
Hafiz Naeem criticised government spending and said Pakistan could not progress while flour and sugar mafias remained active and farmers struggled to obtain affordable fertiliser.
He also objected to what he described as excessive government expenditure, saying officials were using expensive vehicles at the expense of taxpayers.
The JI chief said the nationwide shutter-down strike would begin after August 26, when Eid Milad-un-Nabi (PBUH) will be observed.
The party's sit-ins began on August 16 outside the Punjab chief minister's residence in Lahore and at governor houses in Karachi, Quetta and Peshawar.
The protests come amid growing public concern over rising fuel prices, inflation and electricity bills.
The government recently shifted from a fortnightly fuel price review to a daily pricing mechanism following volatility in international oil markets amid renewed conflict in the Middle East.
The fuel price dispute has also prompted protests from transporters and petroleum dealers.
Earlier this week, the All Pakistan Goods Transport Alliance suspended its nine-day nationwide strike for 40 days after receiving assurances from the federal and Sindh governments on key demands, including petroleum pricing.
The Pakistan Petroleum Dealers Association had also issued a 72-hour ultimatum to the government earlier this month, demanding resolution of outstanding issues and implementation of commitments made by the petroleum minister.
