A man and woman died and five others were injured in the blaze at a house in Withington, Manchester, on 10 February.
More than 3,000 people have signed a petition to try to keep Robert Chilowa, who is from Zimbabwe, in the country.
The Home Office said Mr Chilowa does not need the UK's protection and can return to Zimbabwe safely.
"I came here for political asylum. [Life] was very difficult.
"I left my son and my daughter and my family," said Mr Chilowa, who has been in the UK since 2001.
"There isn't any change [in Zimbabwe] at all...There are still sanctions"
The 46-year-old received a letter from immigration officials on Wednesday telling him he must leave his home in 12 days and is not entitled to claim any benefits.
He has appealed against the decision. "It broke my heart," he said.
A date for deportation is yet to be set, he said.
Mr Chilowa said he helped the children escape from a window of the burning house because "human life matters".
"I was sleeping... and I heard this scream and it was so distressing. A cry for help. I just jumped off my bed and sprung to action.
"When I got there I saw this young girl lying on the floor and she pointed to the window and said 'please save my brother and my sister'.
"You can imagine the heat and it was so so bad, so all I did was I saved them."
Mr Chilowa was taken to hospital for smoke inhalation following the fire and said he has since been for counselling.
"The nightmares will always be there. That voice.
"I didn't know them, but when I heard that cry it touched my heart."
The petition asks Home Secretary Amber Rudd to "consider her decision" and encourages people to sign to "save this gentle giant".
Petitioner Ananias Chakwizira wrote: "This act of bravery is good character especially in today's world whereby he could have chosen to be a bystander and take pictures from afar.
"Robert did not commit any crime but saved lives and deserves recognition."
A man who was hailed a hero for helping save the lives of two children in a fatal house fire is facing deportation.