Verratti was forced to leave the field in the 64th minute of their 1-0 Ligue 1 win at Olympique Lyonnais and PSG coach Christophe Galtier said he would be examined on Monday.
"I am worried because when Marco can't carry on, it's because he's injured," Galtier told reporters.
"He was supposed to join his national team tonight but he will go back to Paris to do some tests.
"It is a blow on the calf, a rather powerful one."
Italy manager Roberto Mancini told reporters that he would not be available when they host England on Friday in Milan before travelling to Budapest to meet Hungary three days later.
"Verratti won't make it," Mancini said. "He took a knock on his calf and can't even walk at the moment. We're probably going to call up Davide Frattesi."
PSG confirmed that Verratti would return to the French club to receive treatment for "a contusion with deep haematoma" of the left calf.
Italy have five points from four games in League A Group 3 and are third behind Germany and leaders Hungary.
