Pakistan and Iran signed a deal in 2010 under which Tehran would supply gas to its eastern neighbour from 2014, with sales to reach up to to one billion cubic feet (28 million cubic metres) per day by mid-2015.
The project envisaged a pipeline, 900 kilometres (560 miles) in length built from Assaluyeh in southern Iran to the border with Pakistan.
Another 800 kilometres pipeline was also needed inside Pakistan to receive gas from Iran's South Pars field in the Gulf.
"We want to complete this project by 2014," Ahmadinejad told a press conference in Islamabad.
"The portion of pipeline on Iranian side is about to be completed swiftly, while on Pakistan side the work will be completed soon," he said, adding that Iran was also extending "financial assistance" to Pakistan for this purpose.
He said Iran was also providing electricity to Pakistan and the two countries have signed agreements for up to 1000 megawatts of electricity supply.
Ahmadinejad also brushed off US pressure on the gas supply project to Pakistan.
"America cannot affect this project....God willing this project will be completed soon and gas will reach Pakistan."
The plans to complete the pipeline in Pakistan have run into difficulty over reluctance by investors who fear they could be hit by sanctions.
Pakistan insists the pipeline is vital to efforts in overcoming the energy crisis it faces, but the United States has expressed strong objections to the project.
It is urging Islamabad to abandon it because of sanctions against Iran over its controversial nuclear programme.
Pakistan, which produces just 80 percent of its own electricity needs, sees the $7.5 billion gas project as a partial answer to the crisis which has led to blackouts and has suffocated industry.
Iran, which has the world's second-largest gas reserves, is rapidly developing its production but can only export a small part of it due to lack of pipelines or liquefaction infrastructure.