Trippier, the subject of a formal bid from the Premier League club, was the last player off the pitch after yesterday’s 2-0 home win over Rayo Vallecano.
The 31-year-old appeared to wave goodbye to fans as he left the field, and manager Simeone addressed Trippier’s situation after the game.
“We have always had to live with these situations,” said Simeone. “It always happened that important players for the team had the chance to leave. Then it will depend on what the player wants – and it’s up to us to adapt to what happens.
“You know very well that once the footballer makes a choice, there is not too much we can do as coaches apart from telling Trippier how important he is for our team. Therefore, we’ll look for solutions depending on what will happen.”
Newcastle hope to conclude a deal for Tripper, in the final year of his contract, in the coming days.
The right-back – who played under Newcastle head coach Eddie Howe at Burnley – is understood to be keen on a move for United.
Howe spoke about his keenness to get at least one deal done early late last month.
“Of course, ideally, you’d want to utilise every day that you have,” said Howe. “Certainly, from our perspective, we know we’re in a hurry, we’re not sat back thinking we’ve got all the time in the world. That’s not where we are in our current position. Every day matters.”