TMZ Sports spoke with Ahmed Abdirzak, a UK resident, who tells us he was vacationing in Miami before Monday's scuffle with the former UFC champ.

Ahmed says he spotted Conor on their way out of the club as he waited for the valet to bring his ride around. Once he saw Conor, Ahmed tells us he pulled out his phone to snap a pic -- and then says Conor actually approached him and appeared to be offering a handshake.

Once he had a hold of his hand, Ahmed says Conor pulled him in and grabbed the phone out of his hand ... allegedly proceeding to stomp on it while his bodyguards blocked off Ahmed. Ahmed asked for the phone back, but to no avail.

He says Conor put it in his pocket, laughed and hopped into a waiting vehicle. Ahmed's pissed about his phone, 'cause he says there's precious content on there for him that he'll never get back.

As you know, Conor was arrested and booked for robbery/strong-arm and criminal mischief, and made bail Monday night. He was calm and collected as he made his way past cameras and into his ride.