"We are demanding you to show compassion to our children, our wives, our husbands and our families," the letter reads.
Refugee advocates told BuzzFeed News they have been overwhelmed with similar letters from people in offshore detention centres since Malcolm Turnbull took office.
In another letter, an asylum seeker on Manus Island begs the PM to "show humanity to us."
"I don’t like begging for anything but your treatment forced me to do it again and again, congrats to new pm please you show us the real Australian treatment not like that guard or immigration officer who assaulted to me and other people in offshore," he writes.
A Senate inquiry into the Nauru detention centre heard there were 67 allegations of child abuse up until May this year. 33 asylum seekers alleged they had been been raped or sexually assaulted at the centre.