Pacquiao spotted his boxing rival during the Lakers' 130-111 loss to the Golden State Warriors on Monday at Staples Center in Los Angeles. Pacquiao had someone film the interaction as he walked up from behind Mayweather's floor seats.
He first tapped "Money" on the shoulder before putting out his open hand. Mayweather looked as though he wanted to fist bump Pacquiao, but the two had a miscommunication when their hands met.
Mayweather finished off the exchange by smirking at his counterpart.
Pacquiao's Instagram post of the sequence had nearly 2 million views as of Tuesday afternoon.
Mayweather (50-0) met Pacquiao (61-7-2) in a mega-bout on May 2, 2015. He has since beat Andre Berto and UFC star Conor McGregor, but hasn't fought since beating "The Notorious" on Aug. 26, 2017.
Pacquiao is 4-1 since losing to Mayweather. He beat Adrien Broner on January 19 at the MGM Grand in Las Vegas.