Galtier said that his team must be wary because of the fact that Montpellier have appointed a new coach, which may motivate their players in Rolland Courbis's first game in charge.
"We'll be in the right third of the table with a win," he told Ligue1.com. "I'm focused on the balance of the side and the determination we need to show in order to win games, especially away games like this one at Montpellier.
"Every time there's a change in coach there's a reaction and people take stock of the situation. We know their players will be more motivated than ever."
Saint-Etienne are currently eighth in Ligue 1 with a game in hand.