Zardari made the remarks while interacting with a delegation of the South Asian Free Media Association at his private residence in Lahore on Sunday night.
The PPP, which led the government at the centre for the past five years, was routed in the May 11 polls by the PML-N.
Asked what he would have done differently about the 2013 polls, Zardari replied he should have resigned from the presidency to steer the electioneering.
He said the PPP's campaign had become leaderless and rudderless due to his constitutional position and various other factors.
Zardari stopped participating in political activities earlier this year because of pressure from the Lahore High court, which ruled that the President was expected to be apolitical and impartial.
He was unable to campaign for the PPP, and his son, Bilawal Bhutto-Zardari, was never seen in public during the electioneering.
The PPP could not conduct a proper campaign in Punjab province because of threats from the Taliban and the judiciary too was against the party, Zardari said.
"The party couldn't fight on multiple fronts simultaneously," he said.
At the height of the campaign, top PPP leader Yousuf Raza Gilani had to shift his focus to his son Ali Haider, who was kidnapped, Zardari said.
Former premier Raja Pervez Ashraf was fighting court cases and other top leaders were detached from the campaign for one reason or the other, he added.
Zardari also blamed the energy crisis for the PPP's poor performance.
"The PPP government could not handle the electricity crisis and this caused the party’s defeat," he said.
Expressing doubts about the transparency of the polls, Zardari said returning officers had played an "important role" in the process. He claimed at least 45 seats were "snatched" from the PPP in Punjab.
In a lighter vein, he said: "If I get these returning officers, I can win the (next) presidential election."
Zardari dismissed reports that he would step down in the aftermath of the PPP's defeat, saying he intended to complete his constitutional term.
He is set to complete his five-year term in September.
"If I did not resign at the time of the elections (to lead PPP's campaign), there is no justification for my resignation now," Zardari told the delegation.
Despite its reservations, the PPP had conceded defeat in the election and would deliberate on the causes of its poor electoral results, he said.
Zardari also said he would administer the oath of office to leaders of the party that has won the mandate.
"The opposition leader will be from the second largest party in the National Assembly," he said.
"We would have no issue if the Pakistan Tehrik-e-Insaf becomes the second biggest party and gets the slot of Leader of Opposition."
The PPP will mull over the factors behind its defeat in the elections in a meeting on Monday.
Zardari said the PPP would remain active as it was impossible to obliterate it from the political landscape.
Zardari arrived in Lahore on Sunday for a two-day visit.
He will meet PPP leaders from across Punjab during his visit.
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