Floyd Mayweather Gives McGregor Ultimatum for Megafight (PHOTO)

Floyd Mayweather says he's not the reason for the hold-up on a superfight with Conor McGregor -- and is pointing the finger at the UFC.

"Listen, Conor McGregor, if you really want to get this fight done ... take care of your business with the UFC and then have your people get in touch with my people," Mayweather wrote.

For the record, Dana White has already offered terms -- $25 mil per fight plus a Pay-Per-View split. Floyd laughed it off and never countered.

As for Conor, he's in Vegas -- which he now calls "My City" -- despite the fact Floyd lives there.