USA boss Gregg Berhalter confirmed he had held "positive" talks with the 18-year-old but Dest is not ready to commit to featuring in competitive matches, which would him bind him to the nation he represented at several youth levels.
Netherlands have expressed interest, with Ronald Koeman said to have engaged the defender in discussions about a change of allegiance.
"I haven't decided yet on either one. I need more time," Dest told Fox Sports after Ajax's victory at Valencia in the Champions League.
"It's a decision I have to make for my entire life, so I want to handle it with care. I need to think carefully, that's why I left it alone this time.
"Hopefully I will have decided by next month but if I need more time I'll take it."
Dest, who was born and raised in the Dutch city of Almere, has been tipped to enjoy a bright future.
Erik ten Hag promoted him to the first team at Ajax this season and has handed the teenager 12 appearances in all competitions.