The two clubs drew 1-1 in New York this morning.
"Certainly we have to take notice of what PSG is doing," said Di Matteo. "They're going to be involved in the Champions League and they could be an opponent to us. And they have signed some of the best players around the world.
"So you do take notice," he continued, "and I think it's going to enhance the competition in the Champions League and it's going to make the French league more interesting by acquiring all these players."