Nigel Smith had been made subject to a sexual risk order in 2017 despite being cleared of allegations which had been made against him.
The order prohibited the former HGV driver of communicating or attempting to communicate with under-18s.
But when police stopped him behind the wheel of a Citroen in Ashington, Northumberland, in July, he was with two 14-year-old girls and another man.
Investigations revealed Smith had said to the other man, who had no idea of the order he was subject to, "have you seen the size of her t***".
The friend became angry at the remark and pointed out how young they were.
He said if he had known about the sexual risk order, he would not have allowed Smith to come into contact with the girls.
Now Smith, who admitted two breaches of the sexual risk order, has been jailed for 13 months at Newcastle Crown Court.
The court heard the civil order had been made by Hastings and Eastbourne Magistrates Court in February 2017 and Smith later moved to Jarrow, South Tyneside.
Sentencing him, Judge Edward Bindloss said: "They felt distressed and intimidated by your actions.
"This was a persistent breach in relation to two 14-year-old females and given the persistence of the breach, it increased the risk of harm to them."
Smith, 58, of Greenbank, Jarrow, who has one unrelated conviction from 2009, was jailed for 13 months and was told the sexual risk order continues until February 2022.
The court heard he had a brain haemorrhage in 2002, has several children and "lived a lonely life".
Richard Bloomfield, mitigating, said: "The order was based on evidence this defendant was acquitted of before the criminal courts.
"He was not present when the order was made and he had no legal advice.
"He didn't appreciate the proper extent of the order, he thought it meant he could not be alone with anyone under 18.
"He has been in custody for four-and-a-half to five months and for a man of his age, it's the first sentence he has served and it's not something he is anxious to repeat."