"Iraq needs weapons and the international community has the ability to provide Iraq with the weapons it needs," he told reporters after a meeting of 21 coalition members in Londozn.
Abadi said the plummeting oil price had been "disastrous" for Iraq, which is on the frontline of the fight against IS militants who seized parts of his country and Syria last year.
He said his presence at the meeting alongside US Secretary of State John Kerry and other foreign ministers was to secure a commitment from the coalition of more help.
"I'm personally here to get more support from our partners," Abadi said.
He said there had been a positive reaction to his request to defer payments on the delivery of munitions and armaments, and said there had also been a recent increase in the delivery of those.
But he stressed: "We don't want to see a military defeat because of budget and fiscal problems."
Abadi was speaking at a press conference flanked by Kerry and British Foreign Secretary Philip Hammond, who both said they would ensure Iraq's security forces had the equipment they needed.
"We've heard very clearly what he said," Hammond said, adding: "This campaign is not going to fail for want of some guns or some bullets in the hands of the Iraqi security forces."