The four were arrested in the wake of Faisal Shahzad's May 2010 attack, which fizzled when the explosives in his vehicle produced smoke but no blast. Shahzad has pleaded guilty and admitted to getting training from the Pakistani Taliban in the country's tribal region along the Afghan border. He was sentenced to life in prison in the U.S.
The attempted attack increased tension between Pakistan and the United States, which has long accused Islamabad of not doing enough to crack down on militants on its soil who pose a threat to the West.
Even though the men acquitted Saturday had been in custody for two years, very few details had emerged about their closed-door trial in an anti-terrorism court in Rawalpindi, next to the capital Islamabad.
Such trials rarely produce convictions in Pakistan because police often lack basic investigative skills, prosecutors lack training in terror cases and judges and witnesses are often subject to intimidation.
One of the men released Saturday, Muhammad Shoaib Mughal, had been charged with providing Shahzad with financial assistance, said his lawyer, Malik Imran Safdar. The other three men, Humbal Akhtar, Muhammad Shahid Husain and Faisal Abbasi were charged as Mughal's accomplices, said Safdar.
Following their arrests, several of the men were also accused of helping Shahzad link up with militants in the tribal region. But those accusations do not seem to have resulted in any charges.
Akhtar's father said he was ecstatic at his son's release.
"I have suffered a lot during these two tough years," said Muhammed Akhtar. "Finally I got justice."
Two other men arrested by Pakistan in the wake of the attempted Times Square attack were previously released. It's unclear if Pakistan has any other suspects in custody.
Human rights groups have long criticized Pakistani security officials for holding suspects for months, even years, without filing charges or divulging any information about their cases.
Most of the men acquitted Saturday come from the same stock as Shahzad — wealthy, urban, educated and with careers in computers, telecommunications and graphic design. Mughal was running a large computer dealership in Islamabad before his detention.
One of the things that Shahzad said motivated him to carry out his attack was U.S. drone strikes targeting militants in Pakistan's tribal region. The strikes are very unpopular in Pakistan because many citizens believe they mostly kill innocent people, an allegation disputed by the U.S.
The strikes have continued to cause tension between the U.S. and Pakistani governments, but American officials have made it clear that they have no intention of stopping the attacks, which they see as vital to fighting al-Qaida and the Taliban.
The latest strike occurred Saturday when a drone fired two missiles at a motorbike in Dogh village in the South Waziristan tribal area, killing two suspected militants, said Pakistani intelligence officials, speaking on condition of anonymity because they were not authorized to talk to the media. It was the fifth such strike in the country in less than two weeks.