The Swede, who had surgery on his right knee at the end of last year, suffered a recurrence this week and was forced to pull out of The Barclays FedExCup series event in New York after shooting a three-over 74 in the opening round.
Clarke, however, said on Friday that the world number four was simply being careful by withdrawing from the tournament.
"I've just had a message from Henrik and he said it was solely precautionary," the Northern Irishman told Sky Sports television.
"I messaged him back telling him that was the best news I'll hear all day. I think he's just being careful.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"The Ryder Cup means so much to him and I think he's just making sure he can play the rest of the FedEx and also make sure he's fit for the Ryder Cup."
Stenson won the first major of his career at Troon in July and followed up by taking the silver medal behind Ryder Cup team mate Justin Rose at this month's Rio Olympics.
The Ryder Cup matches against the United States will be held from Sept. 30-Oct. 2.
(Writing by Mark Greaves; Editing by Tony Jimenez)
