I and Trump 'opposites in some ways': Obama

In rare praise for Donald Trump, US President Barack Obama has said the President-elect is "very engaging and gregarious" and not lacking in confidence but acknowledged that they were "opposites in some ways".

"He is somebody who I think is very engaging and gregarious. I have enjoyed the conversations that we have had. He is somebody who I think is not lacking in confidence," Obama said.

"You have to have enough craziness to think that you can do the job. I think that he has not spent a lot of time sweating the details of, all the policies that I think that can be both a strength and a weakness. I think it depends on how he approaches it.

"If it gives him fresh eyes, then that can be valuable. But it also requires you knowing what you do not know and putting in place people who do have the kinds of experience and background and knowledge that can inform good decision- making. I think it is fair to say that he and I are sort of opposites in some ways," Obama said.

After the November 8 general elections, Obama and Trump have had several talks over phone after their first meeting at the Oval Office days after the elections.

"The conversations have been cordial. He has been open to suggestions. The main thing that I have tried to transmit is that there is a difference between governing and campaigning, so that what he has to appreciate is, as soon as you walk into this office after you have been sworn in, you are now in charge of the largest organisation on earth," Obama told ABC News.

"You cannot manage it the way you would manage a family business. You cannot manage it the way you would manage a Senate office as I was a senator before I became president and so you have to have a strong team around you. You have to have respect for institutions and the process to make good decisions because you are inherently reliant on other folks.

"So when I talked to him about our intelligence agencies, what I have said to him is that there are going to be times where you have got raw intelligence that comes in and, in my experience over eight years the intelligence community is pretty good about saying. look, we cannot say for certain what this means," the US President said.

He said that "there are going to be times where the only way you can make a good decision is if you have confidence that the process is working and the people that you put in charge are giving you their very best assessments".

Not lacking in confidence, Obama said, is probably a prerequisite for the job.