Having vowed to bolster team discipline, coach Laurent Blanc has said he will be demanding "explanations" from the pair, who have both been linked with moves away from the French capital during the January transfer window.
They were notable absentees from a winter training camp in Morocco which culminated in a 1-0 friendly win over Inter Milan on Tuesday and neither player appeared at Friday morning's first training session of the new year at the club's base in the Paris suburbs.
They both only arrived back at Paris' Charles de Gaulle airport on a flight from Buenos Aires at the same time as the training session started at 10am.
Argentine Lavezzi finally arrived at the PSG training ground in his Ferrari four hours later, while Uruguayan Cavani followed about 10 minutes after that.
After the pair had failed to show up in Morocco, Blanc said he would want "some explanation" from Cavani and Lavezzi.
Blanc refused to be drawn on a possible transfer of either player, however.
"We can't say that today. We're going to wait until they arrive," he said. "We'll expect some explanation, and then we'll make sporting decisions as a club."
Blanc said just before France's winter break that Cavani lacked "confidence" and was going through a "difficult" time.
Arsenal have been linked with a move for the forward, although he would probably cost at least €50 million ($60m).
Inter Milan coach Roberto Mancini, meanwhile, has denied any contact with Lavezzi.
Blanc on Sunday vowed to toughen "discipline" within the squad with PSG sitting in third place in Ligue 1, behind Lyon and leaders Marseille, at the season's halfway stage.
"There are certainly some little things that will change, some privileges that will disappear," he said.