Eight years ago, New Zealand offered to resettle 150 refugees a year from Australia's offshore detention system.
Williams is urging Morrison to finally accept the offer.
"I think 250 people or close to, have been left in Papua New Guinea and in Nauru that can be brought to have a better life.
"They've been stuck for the last eight years. We can't even do it for two weeks in quarantine, imagine doing it for eight years."
He told Morning Report that New Zealand needed to understand the meaning of refugees.
"These refugees, a lot of these people are doctors, architects, they want to be contributing people in society but they are being forced to flee their homes.
"I know the narrative out there is we try and portray these type of people as criminals almost and when I seen [sic] them first hand, these people they just want a better life."
But at this stage, Morrison did not want to sign the deal, Williams said.
"I'm not a politician and I'm far from being involved in politics.
"I'm a humanitarian and when I see something that's not right as a human I use my voice to stand up and say what's wrong."
He said since 2013, "$10 billion" has been spent on refugees in these islands.
"The last year alone ... spent $800 million on 250 refugees. I can't fathom that."
He said he had a long history of being involved with refugees.
"I went and visited a Syrian refugee in Lebanon back in 2015 and I [have] seen their struggle first hand. The thing that really touched my heart was that these people are just like us, they're humans."
Prime Minister Jacinda Ardern met Morrison for formal talks today.
She told Morning Report issues of deportation and refugee pathways to citizenships would be "traversed" in conversations with Morrison.
"There are now New Zealanders who have been in Australia for five years who are not eligible to access that, that's something that I'm going to raise.
"The 150 [refugees intake offer has] been on the table consistently and it still stands."