The cash was seized and the matter referred to the the Income Tax Department, an official said.
Acting on a tip-off that the trio was trying to exchange demonetised currency notes with new bills for a commission, the police detained them when they arrived near a hotel on Madhpar highway in a car.
"We detained three persons who arrived in a car and were waiting for a customer who had contacted them to exchange their demonetised currency notes," said J M Ala, Inspector, Local Crime Branch (LCB) Kutch (West).
"They did not furnish any documents to support the possession of money. We detained them and seized the money. The Income Tax Department has been informed and it will further investigate the matter," said Ala.
The trio was identified as Irfan Mistry, Abdul Odiyan and Imran Majotha, he said.