Rangers are said to be lining up a £500,000 offer for the centre-back at the end of the season.
But Robinson insists that he has not heard of any official interest in the defender yet.
"There's been no official bid from anybody. Pedro hasn't picked up the phone to me or anyone else,” the Motherwell boss said.
"Ben is someone we want to keep but don't get me wrong, we are a club that sells players. We bring players in on low, low money, put them back out again and then start the process again.
"Good players attract interest but it won't affect Ben in any shape or form. He's a brilliant, brilliant kid. A super boy whose feet are on the ground and I know he'll give everything for Motherwell.”
Rangers are known to be targeting new defenders in the upcoming months, as Caixinha looks to improve his squad.
Rangers are set to allow both Clint Hill and Philippe Senderos to leave Ibrox (The Scottish Sun), to make room for new defenders to join.
Caixinha has reportedly been impressed Heneghan’s form this season, with the 23-year-old playing an important role for Well.
Heneghan has played in all but one of Robinson’s side’s league matches this campaign, and even though Well’s results haven’t been particularly positive, the defender has still done enough to catch the eye.