White told TMZ "he's heard the rumors" and said "if Brock is 'seriously interested' in fighting Jones, he's more than happy to put it together."
Lesnar has split time between WWE and UFC over much of the past two decades. He was most recently under contract with WWE and fought at WrestleMania 36, but he's no longer under contract with the promotion, per Mike Johnson of PW Insider.
Therefore, he is hypothetically free to fight in the UFC, even if it's for just one bout.
Jones called out the former UFC light heavyweight champion after his win—which later became a no-contest—over Daniel Cormier for the belt in July 2017:
Jones, who has lost just once in his illustrious career, is looking to take on new challenges. He's done all he can in the light heavyweight division and has given up his belt to make a move to heavyweight, where he's looking to challenge Stipe Miocic for the title:
For good measure, he called out Lesnar once more:
Lesnar has not fought in the UFC since 2016 when he beat Mark Hunt. That result was overturned because of a positive test for performance-enhancing drugs, however. He went 5-3 lifetime with one no-contest in the Octagon, beating Randy Couture for the heavyweight title and defending it successfully twice before dropping the belt to Cain Velasquez.
Jones is 26-1 lifetime with one no-contest. He has won the UFC light heavyweight belt on two separate occasions and defended it successfully 11 times.