Benitez's side were beaten again on Super Sunday, this time 1-0 at fellow newly-promoted side Huddersfield, and the Spaniard has previously said this summer that he would have liked to have spent more money.
When asked about the transfer situation by Sky Sports after the defeat, Benitez was short, and predicted a difficult remainder of the window.
"We will see what happens, it's still 11 days, but I don't see an easy window yet."
Regarding the defeat, Benitez partly blamed defensive injuries for their performance, and said it is a learning curve for their players in the Premier League.
"I'm obviously disappointed. We have some little problems in defence, with not too many players, and we have to manage.
"They did well for a while, and we conceded because we gave them too much time on the ball. After that we were quite positive, but it's a learning process for us."
Graeme Souness said after the game on Sky Sports that the defending for Huddersfield's winner was "like kids' football", and Benitez agreed when asked if more could have been done to close down Aaron Mooy.
"Yes, clearly. This is the Premier League, you cannot make mistakes, and you have to take your chances if you make chances."