The Uruguay international only signed for the Ligue 1 champions last summer in a £50m deal, but despite helping them to a second successive title he is said to be unhappy in the French capital.
Cavani is primarily a centre-forward, but to accommodate Zlatan Ibrahimovic in his favoured role he was shifted on to the left flank last term.
This has led to talk that he could be off, which has alerted United.
The Red Devils have been linked with the classy attacker over the past few months, but their interest was thought to have cooled.
However it has now emerged that discussions with PSG are bubbling away.
Talks are believed to be focused on his wage demands and whether or not he’d be ready to sacrifice Champions League football to switch to Old Trafford, which could then be followed by negotiations regarding a fee.
It’s likely that United would have to pay around £50m for the South American, which would seal Javier Hernandez’s future – the Mexican is believed to be close to leaving.