Mbappe and Dembele could not find a way through against stubborn opposition
PSG were held to a goalless draw at the Gabriel Montpied by a Clermont Foot side who frustrated the Parisians' onslaught.
Luis Enrique's team dominated the game but were a little too cold in front of goal. Mbappé hit the woodwork and Diaw saved from Gonçalo Ramos to deny the visitors a late winner.
PSG, who face Newcastle in the Champions League on Wednesday, remain second in Ligue 1, one point behind Brest, who have a game in hand.
The first 20 minutes of the game were a siege. Achraf Hakimi's surges up the right flank caused a lot of disruption in the Clermont defence. The Parisians' clearest chance came from the head of Randal Kolo Muani, who nodded over the crossbar from a great cross from the right.
The home side reacted and improved as the minutes went by. Konaté and Nicholson took responsibility for their team in attack and made the visitors' defence uncomfortable. Luis Enrique's side responded to Clermont's initiative with a very intense last stretch of the first half.
Dembélé and Mbappé had a number of individual moves that could have led to PSG's first goal, but Pascal Gastien's defensive unit remained solid.
The momentum continued after the break and Mbappé came close to opening the scoring. The French star sent the ball against the right-hand post from a clear-cut chance inside the box.
Luis Enrique's side continued to search for a goal against a Clermont side who kept their low block in order to create counter-attacks. After the hour mark, the Spanish coach turned to the bench and brought on Gonçalo Ramos and Zaire-Emery to freshen up the team. The Portuguese striker could have given his side the win in the dying minutes, but Mory Diaw saved with a fine save.
The Parisians claimed two penalties after Mbappé and Kolo Muani were brought down inside the box, but the referee waved them away and Clermont earned a point against a PSG side who continue to fail to convince their fans.