A Syrian migrant taken from Lesbos to Italy by the Pope says she's grateful for the chance to start a new life.

The Pontiff took 12 people back to Rome with him following a visit to the Greek island last week.

Nour Essa - who was a microbiologist in Syria before the war - says she'd like to go back to her home country, but she's happy Pope Francis has given her family this opportunity.

"We didn't believe it," she said.

"He is a very kind man, he is very nice. We greet him, and we said to him 'thank you'. There is no Muslim leader, or Arab leader, or has done the same for us."

Initially, the Pope had hoped to bring a mixture of Christian and Muslim families, but only those who arrived before the 20 March deadline in which refugees are deported back to Turkey could be eligible.

In the end, 12 people, all Muslims, boarded the papal plane.

Nour Essa, her husband Hassan and Riyad travelled through Islamic State-controlled land before reaching Turkey.

Smugglers facilitated their journey through Turkey and across the Aegean Sea in a dinghy to the Greek Island of Lesbos.

They say they left Syria because they wanted a future and because Hassan's Syrian future was either to fight for the Syrian Army or the Islamist extremists, or leave.

"I didn't want to go to with any side: not for the government, neither for (an) Islamic group," Hassan said.

"I am a human, I am not an animal. Killing just for animals. I am not an animal, I am a human, I like to live."

The Pope's decision to bring three families back to the Vatican with him after his visit to the Greek island of Lesbos last weekend surprised all but a small group of Vatican officials and Catholic charity workers who organised the gesture.