Backed by the millions of their Qatari owners, PSG have become a dominant force in French football in recent years, winning back-to-back league titles as well as last season's Coupe de la Ligue.
Their Champions League run was ended by Chelsea at the quarter-final stage in the previous campaign and, ahead of the rematch in the last 16 this time around, Mourinho confirmed he has been approached by the club in the past.
"I know the PSG project well, I know it well because when they start this project with the owner, the president and Leonardo, I was to be the coach," he said.
"I met them in Qatar, so I know the project well. The project was to start dominating in France, to dominate in Europe. The domination in France is there, they are champions, champions, champions.
"They are in the League Cup final, they are in the quarter-finals of the French Cup, they are two points behind the leaders [this season] so the domination of France is there.
"They want to dominate in Europe too and, to be fair, you look to Paris in the last two seasons in the Champions League and they lost in the quarter-finals, once narrowly to Barcelona and last season against Chelsea in the last second.
"So they know and they feel they are there. They are there. Paris is a big team with big ambitions."
Mourinho revealed the reason he turned down the offer was because he wanted to stay and win La Liga with Real Madrid.
"Because I was in Real Madrid and it was a real ambition for me to be champion in Spain, England and Italy," he said.
"It was a big challenge for me and a big challenge to compete directly against the best, Barcelona, probably the best team in Europe for the last decade for sure. It was not the right moment for me to go."
