The Toffees face Bournemouth in the Premier League on Saturday and are priced 4/6 to record their second win in four days.
Koeman has been under pressure after Everton lost four games in a row without scoring a goal, but he believes the expectations placed on his side this season are unrealistic.
“I know what we are and I know the way to be successful,” he told ESPN.
“It’s crazy to put a lot of pressure on the team by saying we need to finish in the top four. In my opinion, that’s ridiculous.
“Everybody has signed new players. We signed some young players, and (on Wednesday) we played with six or seven boys of 19, 20, 21, 22.
“That is the future, it needs time, and that is normal. Let’s make the next step.
“It doesn’t mean we don’t have ambition, but I’m realistic – and in football, being realistic is sometimes difficult.”
Everton ran out 3-0 winners against Sunderland on Wednesday and are 12/1 to repeat that scoreline this weekend.
Koeman admitted he was relieved to pick up a victory and is hoping for more of the same against the Cherries.
“Let’s hope it will be a positive turning point, what we need,” he added.
“Now Saturday is really important. Now we need to show we are still strong, and I’m confident after what I saw.”
Everton head into the game 18th in the table and Koeman remains as low as 5/2 to be the next Premier League manager to leave his post.
Anything less than a victory against Bournemouth would intensify the pressure on the Dutchman, although the club have indicated they are prepared to give him time to turn things around.