Tom Selleck Says He Danced with Princess Diana to Calm John Travolta Gossip

Tom Selleck once jumped to Princess Diana's aid by taking her for a spin on a dance floor -- and he says he did it to spare her from petty gossip about John Travolta and her.

The actor tells this interesting story in his new memoir, 'You Never Know' ... explaining he was lightly cajoled into slow dancing with the late Princess of Wales in 1985 at a White House state dinner in order to ward off rumors she and Travolta were hooking up.

The way Selleck tells it, he was minding his own business -- hanging with Clint Eastwood in the East Room -- when Princess Di and the "Grease" actor decided to hit the dancefloor for a second time, and a woman rushed up to them speaking rapidly.

Tom says this person told him Di and John dancing again could lead to rumors the 2 fancied each other ... and, firmly asked if he could step in to replace Travolta.

Selleck shot that idea down real quick, saying there's no chance he'd cut in on a groovin' JT ... and, instead compromised by agreeing to dance with the Princess after the song ended.

TS says he was super nervous to cut a rug with Diana after her dance with Travolta. Thankfully, a slow song came up next and Selleck says he didn't have to match John's impressive dance moves.

Tom describes Diana as a shy girl in the book though he adds she was a tremendous conversationalist ... an area in which he admits he fell short that particular night.

Selleck says his then-girlfriend, now-wife Jillie Mack, danced with the then, Prince Charles, for a song ... and, when it ended, Clint tagged Selleck out and took up the role of Princess Diana's partner. Quite the star-studded night on Di's dance card!