United took the lead from the spot in first-half injury time, Wayne Rooney tucking home on a rare start.
But it was how they'd won the penalty that so angered Swansea, with replays showing that Rashford was already going down as Lukasz Fabianski pulled his arms away, only for the teen striker to dangle a leg and manufacture contact.
"I’m not saying he cheated," offered Clement on the incident, "I’m using the word ‘deceived.’
“Maybe cheat is a word I’d use another time but on this occasion I think he deceived the ref.
“I looked at the reaction of my players at the time and they were furious so that puts doubt in your mind.
“And also there was a delay between the contact - or non-contact - and the decision being given.
“The replay showed the player deceived the referee, there’s no other way to look at it.
“You can say he dangled his leg to make contact but he actually went down before that. The keeper pulled out of it.”
Swansea thought they should have had a penalty themselves when Martin Olsson appeared to be fouled by Ashley Young in the box, but eventually grabbed what could be a crucial away point when Gylfi Sigurdsson curled home a free kick with 10 minutes to go.