Had they won, they could have closed the gap to PSG to just four points before their Sunday match against Lyon.
This was the third time in five league games that Marseille has dropped points, and they could now be overtaken by third-placed Lens when they play Rennes on Saturday. Montpellier took the lead in the 12th minute through Arnaud Nordin, who finished off a quick counter-attack after a brilliant burst from Wahbi Khazri.
Marseille managed to equalize just before half-time, with Matteo Guendouzi scoring a penalty awarded for handball. However, they struggled to create chances and Khazri went close to a winner for Montpellier midway through the second half, only to be denied by home goalkeeper Ruben Blanco.
Marseille dominated possession in the latter stages of the game but failed to find the winner that would have given them hope of winning their first league title since 2010, especially after PSG's shock home loss to Rennes before the international break.