Mayor Bloomberg said yesterday there would be “very serious” consequences for the city’s budget if the courts blocked the sale of 2,000 yellow cab medallions worth more than $1 billion.

“It is worrisome,” he said. “If it were delayed a little bit it would be difficult . . . If we were to not get it, it would be very serious.”

Manhattan Supreme Court Judge Arthur Engoron stunned the administration by issuing a temporary restraining order on the grounds that the plan had been approved by Albany without input from the City Council.