Rumours have suggested Benitez could replace Vicente del Bosque - who intends to leave his post after Euro 2016 - as Spain coach.
Benitez took over at St James' Park last month on a three-year-deal but with a clause allowing him to leave should Newcastle be relegated from the Premier League.
In the three games he has overseen Newcastle have earned just one point and are six adrift of safety following last weekend's dramatic 3-2 defeat to Norwich.
However, when asked about the Spain job, Benitez said in a media conference ahead of Saturday's visit to Southampton: "I am Newcastle United manager and want to be here next year. I want to be here a while."
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Pressed if he would remain on Tyneside should Newcastle drop into the Championship, Benitez replied: "I have confidence we can stay in the Premier League.
"The team are giving everything. They have to stop the mental block they have.
"There are things we have to learn. The only way to do that is to practice every day. The effort is there.
"[There are] 21 points still to play for, so we have to concentrate just on this game. Get three points if we can [against Southampton].
"If we cannot win we have to keep fighting right until the end. That is our message to the fans - we will not give up."