He later blamed her for "not leaving me alone", in comments a judge has described as demonstrating a lack of remorse.

Habib Atai, 26, was sentenced in the ACT Supreme Court on Friday morning to a partially suspended 15-month jail term for engaging in sexual intercourse with a child.

While the custodial part of the backdated sentence has already expired, Atai must remain behind bars because he has previously been refused bail on unrelated charges.

In sentencing, Justice John Burns said Atai and his victim had met through a mutual friend and begun exchanging messages on Snapchat.

These included "declarations of love for one another" and plans for the victim to visit Atai at his home.

Between April and May this year, the victim went there five or six times.

"She told police that on each occasion, [Atai] asked her to have sex with [him]," Justice Burns said.

"She told [him] that she did not want to have sex."

But Justice Burns said that on one occasion, the pair did have sex.

He indicated that the parties to the case accepted that there was "a true sense of affection" between the duo, and that there was no dispute that the victim had ultimately engaged in sex willingly.

But Justice Burns noted that that did not mitigate the offence because the law recognised that people under 16 lacked the maturity and experience to provide informed consent for sexual activity.

The judge said Atai had known how old the girl was, while he had also lied to the victim about their significant age gap by claiming he was only 23.

While the girl did not provide a victim impact statement, Justice Burns said "it may be presumed that harm is likely to arise for [her] because of this conduct, even if it is not immediately apparent to the victim".

He described the objective seriousness of the offence as being "on the border of low- to mid-range".

The judge went on to explain that Atai had been born and raised in poverty in Iran, where his family had "a long history of persecution and trauma".

While Atai moved to Australia for a better life in 2017, he has had ongoing issues with illicit drugs and was disciplined in jail earlier this month after fighting with a fellow detainee while on remand.

Justice Burns also said it was disappointing that Atai, despite having accepted in court that he knew the victim was 14, told the author of a pre-sentence report that he was unaware of her age and that "she looked older."

"You blamed her for not leaving you alone," the judge told Atai.

"[This] demonstrates a lack of remorse ... and a failure to completely accept responsibility for your actions."

But on the plus side, Justice Burns said, Atai had "a good history of employment" and had worked from a young age to financially support his family.

He said he was satisfied that Atai had prospects for rehabilitation, so long as he addressed his attitude to the offending and his substance abuse issues.

Justice Burns ultimately imposed the 15-month jail sentence, but backdated it to take into account that Atai had already served a little more than six months behind bars on remand.

He also ordered that the remainder of the custodial portion of the sentence be suspended immediately, with an 18-month good behaviour order to take effect in its place.

But Legal Aid lawyer Jan de Bruin told the court that Atai would have to stay in the Alexander Maconochie Centre for the time being, with other charges still pending.