Von Miller is apparently threatening to sit out the 2016 season if he can't get a new deal done with the Denver Broncos. 

Miller just posted on Instagram -- "'I love my Teammates, Coaches, and My Fans' but there is 'No Chance' I play the 2016 season under the Franchise tag."

The Broncos used the franchise tag on Miller back in March -- which means he'd make the average of the top-salaries of his position for the year ... which is roughly $14 mil. 

But Von wants more ... WAY MORE ... recently shutting down a 6-year $114 million deal with $40 mil guaranteed.

And if he doesn't get it ... Von says straight up -- he ain't playin'.

It's a much different stance than he took during an interview that surfaced Wednesday with Chelsea Handler -- in which he stated he would NOT sit out the season.