He said that the process of buying US jets had been "long-winded" and that the militants' advance could have been avoided if air cover had been in place.
Isis and its Sunni Muslim allies seized large parts of Iraq this month.
Mr Maliki was speaking to the BBC's Arabic service in his first interview for an international broadcaster since Isis - the Islamic State in Iraq and the Levant - began its major offensive.
"I'll be frank and say that we were deluded when we signed the contract [with the US]," Mr Maliki said.
"We should have sought to buy other jet fighters like British, French and Russian to secure the air cover for our forces; if we had air cover we would have averted what had happened," he went on.
http://www.bbc.com/news/world-middle-east-28042302
More kind words for the American government. Like so many have said, all the makings of Vietnam 2.0