The matter pertains to CBI's ongoing probe into the alleged sting operation purportedly showing Rawat negotiating a deal to buy support of disgruntled Congress MLAs to save his government earlier this year.
Rawat has written to the apex investigating agency expressing his inability to appear before it and sought a fresh date for the purpose, his media advisor and spokesman Surendra Kumar said.
He had been served summons by the CBI on Friday last, asking him to appear before it today.
This is the second time that Rawat has been summoned by the CBI on a Preliminary Enquiry (PE) registered by it in last seven months. He had earlier appeared before the agency on May 24 during which he was questioned for nearly five hours.