Lamar Odom is not romantically involved with transgender actress/model Daniiellè Alexis ... despite a few social media posts sparking speculation they're dating.

Sources close to Lamar tell TMZ ... the former NBA player is currently single and is not seeing Daniiellè, but they do know each other and are friendly -- which is pretty clear from her social media.

We're told Lamar and Daniiellè met back in June when he was in L.A. for the BET Awards. Our sources say Lamar was shopping when a car pulled up, Daniiellè hopped out and asked for a photo ... and afterward, they exchanged numbers.

They kept in touch, and when he recently moved back to L.A. they grabbed lunch together because they were both in town. Daniiellè's an aspiring actress, and our sources say they typically chat about the industry.

Daniiellè's posted a couple photos of Lamar, which got the dating rumor mill going ... but we're told they are just friends.

BTW, our sources also tell us Lamar has no problems with the transgender community, in general, and obviously has no issue with Daniiellè being a transgender woman -- there's simply no romantic spark between them.