The Chelsea manager is thought to be eager to bolster his attacking options, with the likes of Fernando Torres, Samuel Eto'o and Demba Ba all failing to hit top form this season.
Ibrahimovic and Cavani have excelled for PSG in Ligue 1 this campaign, with the former topping the goalscoring charts on 22 league goals, while the latter has netted 13 in his debut season at the club.
Mourinho worked with Ibrahimovic during his tenure in charge of Inter, but believes that a deal would be "impossible".
"Ibrahimovic? It's impossible," the Portuguese told Canal+.
"He's happy in Paris. I know because we're in contact, we're friends.
"With their financial potential, I don't think Paris will ever open the door for him to leave."
On Cavani, he added: "Cavani is a very good player. But Paris paid a lot of money for him and he has an amazing contract.
"Maybe it's not impossible like Zlatan, because I think that Zlatan is more important to the structure of the club. But I think that it's also difficult."
Mourinho also refuted suggestions that star forward Eden Hazard could leave Stamford Bridge for Laurent Blanc's men.
He added: "Eden is our lad. We want to build the team around him."
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