The girl was taken to hospital with stomach pains in October after telling her mother she was raped near her home.
The boys, who were both 10 at the time and cannot be named, were each found guilty of two counts of attempted rape after an Old Bailey trial in May.
The pair, who had denied all charges, was cleared of raping the girl.
Defence barristers had said the boys were just being naughty or playing a game like doctors and nurses.
Sentencing them, Mr Justice Saunders said he rejected this claim.
He told them: “I do not accept that what happened was a game but I do accept that you did not realise how serious what you were doing was.”
Passing down the supervision order, the judge said that to impose any sort of custodial sentence would be “counter-productive” and not in the best interests of the boys.
He added both boys would be ordered to sign the sex offenders register for two-and-a-half years.
Their mothers, who were both given 12 month parenting orders, will be required to notify the authorities of their sons’ whereabouts
Speaking about the victim, the judge said: “Everyone will sympathise with her for what she has gone through.
“Not only what happened to her as the victim of these offences, but also to have to give evidence about them.
“I hope that she will be given all the help that she undoubtedly deserves to get over her experiences.”
During the trial, jurors heard how the boys had lured the girl into some flats, then took her into a stairwell, a lift and a bin shed before continuing their assault in a field.
The girl, who gave evidence via videolink, said the pair threw her scooter into a bush and refused to retrieve it unless she did what they told her.
The way the case was handled was later criticised by some commentators who called for changes in the way children are dealt with in criminal courts.
Last month, the boys lost a Court of Appeal challenge against their convictions but Lord Justice Hughes spoke of his “dismay” that the three children should take part in a crown court trial.
Mr Justice Saunders said after sentencing that he would submit a report to the Lord Chief Justice on “what lessons I believe should be learned from this case”.