The centre-back's agent has previously revealed that the Red Devils have been in touch about a possible move, hinting at further developments in the summer.
And while the Brazilian is glad to know that PSG rely on him heavily enough to refuse to negotiate such a transfer, he welcomes the attention of Louis van Gaal's side as "validating".
"I'm calm, concentrated. I leave all this to my agent," Marquinhos told L'Equipe.
"Before, PSG refused to begin negotiations. They have shut the door. I see this as something to take confidence from.
"It proves PSG count on me but, to be honest, it gives me pleasure to see Manchester United are interested in me. It's validating."
The French club are looking to build on a 1-1 home draw with Chelsea to progress from the last 16 of the Champions League and Marquinhos is satisfied with their position in the tie.
"We produced a good performance but we must keep our feet on the ground," he observed. "We have to score there but it's no worse than that.
"We know we can do it, unlike last season, when we were caught between attacking and defending. It's good to go without a guarantee. It's easier to motivate the team. I like this situation."