The Spaniard was given a hostile reception in his first game in interim charge in Sunday's goalless draw with defending Premier League champions Manchester City as the home faithful protested against the appointment.
Benitez has succeeded Roberto Di Matteo, who was sacked despite winning the UEFA Champions League and FA Cup last season.
The former Liverpool boss' past rivalry with Chelsea has also damaged his popularity in London but Cech wants a united front.
The goalkeeper told Sky Sports: "Unfortunately you can't change history.
"We had a lot of rivalry against Liverpool but he (Benitez) is here to try to change things, put us in a winning mode, and he needs to get a chance to prove he deserves the chance."
Cech also regrets the sacking of Di Matteo after the Italian paid the price for just two wins in eight games in all competitions.
He said: "It's always bad news as a player, because you are responsible if you don't do well. Unfortunately you can't change the whole team and the manager is the first to go.
"Today (Sunday) was about starting from zero again and getting a positive result.
"You need some time when you change the manager to get a positive result and mood and 0-0 against the champions is not a bad result."