Sunday's 1-1 draw with Lyon extended PSG's unbeaten start to the season in all competitions, but the French champions have not won since thrashing Saint-Etienne 5-0 last month.
Laurent Blanc's men sit three points adrift of early Ligue 1 leaders Marseille, and were held to a 1-1 draw in last week's UEFA Champions League opener against Ajax.
Edinson Cavani's third league goal of the campaign looked to have given PSG all three points on Sunday, but Samuel Umtiti earned Lyon a draw with an 84th-minute equaliser.
And Sweden captain Ibrahimovic, who has not scored in his last four games for club and country, has urged PSG to up their intensity to turn draws into wins.
"We were unlucky today we should have closed the game [out]," he said. "But we didn't and then we concede a goal in the last five minutes.
"We tried to score [to make it] 2-1 but we didn't succeed.
"So we need to work hard and come back."