Defence lawyer Brenda Weksler told a court in Las Vegas her client Michael Sandford, from Dorking, Surrey, was in a "delicate mental state".
Court papers said he had been on suicide watch at a detention centre.
Mr Sandford's mother Lynne, who was not in court for the hearing, wants him to return to the UK for psychiatric help.
Prosecutors allege Mr Sandford, 20, tried to grab a police officer's gun to shoot Republican presidential candidate Mr Trump at a campaign rally in Las Vegas on 18 June.
They also claim he practiced shooting at a gun range the previous day.
His trial has been scheduled for 3 October.
The Associated Press news agency said the meeting was also expected to include Ms Weksler and Ms Sandford's London lawyer Saimo Chahal.
US magistrate judge Cam Ferenbach said the meeting "might help in the resolution of the case in a way that benefits the defendant and the government", the agency reported.
Ms Sandford has said her son has autism, OCD, severe depression and would face up to 30 years in prison in the US.
She argues he should serve any sentence in a psychiatric hospital in the UK to receive help closer to his family.
He has denied charges of disrupting government business and official functions and being an illegal alien in possession of a gun.
The mother of a Briton accused of trying to shoot and kill Donald Trump has been given permission to visit him in custody in the United States.