Spurs cut the Blues' lead at the top of the table to seven points with a 3-2 victory over Koeman's side at White Hart Lane this afternoon.
Harry Kane's brace appeared to have put the north Londoners on course for a straightforward win but Romelu Lukaku hit back for the Toffees while Dele Alli and Enner Valencia both scored in a frantic finale.
Mauricio Pochettino's side are Chelsea's closest challengers but while Koeman is a big fan of the north Londoners' playing style he is adamant Antonio Conte's team have enough in the tank to get over the line.
"I think Tottenham is really strong. It's a difficult system to play against - Chelsea are playing out of the same system.
"It will be very difficult with the distance in points. I think Chelsea are too strong for the rest," he added.
Everton, meanwhile, are still fighting for a European place, despite seeing their eight game unbeaten record ended in N17.
And Koeman, who took charge at Goodison Park last summer, believes he can match Pochettino's achievements for Everton if he is given enough time.
"If you compare the two teams of this afternoon its the third season of Pochettino at Tottenham. If we get that time in Everton then we can make the next step.