Paul Chapman began speaking to the profile over a social chat site which was designed for people 18 years and older.
However, Newcastle Crown Court heard that the 37-year-old continued the conversations after being informed of the decoy's age.
Prosecutor Paul Caulfield said Chapman was arrested by means of citizen's arrest in December, 2018, after enough evidence had been gathered.
Chapman was actually in conversation with a member of the undercover group Secretly Tackling Online Predators, the court heard.
Mr Caulfield said: "Very quickly it became apparent she was in fact pretending to be 14 and the relationship evolved from the 3rd of November 2018 to itsconclusion on the 12th of November.
"The conversation between them developed into conversations of an explicit, sexual nature.
"The conversations became more and more sexual and inappropriate as time goes on."
The court heard the nature of the conversation included what Chapman intended to do the girl if and when they eventually met.
Material obtained from the conversations were then passed on to the Child Online Safety Team who then arrested Chapman at his address.
Chapman, of Etal Cresent, Jarrow, pleaded guilty to attempting to engage in sexual communication with a child.
The court heard that details were passed onto the police and immediate admissions were made where Chapman said: "I'm stupid. I did this because I'mlonely, I wasn't really going to meet her.
"The app site said she was 18 but she did tell me she was 14."
However, Judge Robert Adams was satisfied that Chapman could be dealt with by means of a rehabilitation order.
The judge told him: "Over three years have now elapsed since your offending.
"You were of good character and you have not been in further trouble since.
"The person you were communicating with was in fact a decoy.
"You say you had no intention of actually meeting this person. Still, nevertheless it's a serious matter.
"Your remorse is clear. You are ashamed of your behaviour and the effect it has had on other people.
"The risk of reconviction is deemed as low not least because of the effect your arrest upon you. In my view you are capable of rehabilitation."
The judge sentenced him to a three-year community order alongside a 90 day sex offender's programme and 20 days of rehabilitation requirements.
Chapman must also be subject to a sexual harm prevention order and the sex offender's register for five years.