The court awarded $ 123.34 million for physical and emotional damages to the plaintiffs, four of whom were not present at the bombing but whose relatives were affected.
It also awarded $300 million in punitive damages against the government of Iran, court papers indicated.
In its ruling issued on 10 September, the court said it arrived at a "default judgement" since the defendants - the Islamic Republic of Iran, the Ministry of Information and Security (MOIS) and the Iranian Revolutionary Guards - failed to attend a January hearing.
Reacting to the ruling, a spokesman of an Iranian-backed Palestinian rights organisation In Tehran said Kuwait and Saudi Arabia also backed Hamas and questioned why only Iran was being targeted.
"It is an illegal act of the United States court against the Iranian people," said the spokesman on condition of anonymity.
The case stems from the 4 September 1997 human bombing at the Ben Yehuda Street pedestrian mall in Jerusalem that killed five people and wounded nearly 200 others, including eight of the plaintiffs who filed two separate lawsuits in 2000 and 2001 which the court later consolidated.
"It is an illegal act of the United States court against the Iranian people"
Iranian-backed Palestinian rights organisation
Three human bombers - each carrying bombs "with nails, screws, pieces of glass and chemical poisons," - were involved in the blast. Two Hamas members were arrested and convicted of planning the attack.
Based on past court rulings in similar cases, the court concluded that Hamas "has a close relationship with Iran" and that Iran provided training and economic assistance to Hamas.
Witnesses called as experts to the hearing testified that Iran's MOIS spends between $50 million and $100 million a year sponsoring activities of various organisations such as Hamas.
The damages awarded to the eight plaintiffs include compensatory damages for physical, psychological injuries and loss of prospective income.
The punitive damages awarded, it said, were based on longstanding precedent. As per this, the court applied the multiple of three times Iran's annual expenditure on groups like Hamas, resulting in $37,500,000 for each plaintiff present at the bombing.
An estimated $10 billion (the US contests this figure) worth Iranian assets have been frozen in US banks since the 1979 Islamic revolution.
It was around $12billion, but in the 1981 hostages release deal, the US returned an amount believed to be around $2 billion.