Machsom Watch has sent a written apology to the soldier's commander.
Soldiers told Ynet the incident occurred at the beginning of the month at a checkpoint near Tul Karm. A Machsom Watch activist approached the soldier as he asked two Palestinians to queue for inspection and launched a verbal attack against him.
"She promptly approached him and swore at him, told him he is a 'Nazi' and a 'beast'," soldiers told Ynet.
Soldiers who were present at the checkpoint at the time said their comrade acted according to IDF regulations and the activist's reaction was inexplicable and "degrading."
"There are a lot of situations where we carry on as usual and don't respond, but this was too much and he was offended," soldiers said.
Police said they are currently searching for the activist who is wanted for interrogation.
In the written apology sent to the soldier's commander the Machsom Watch activist wrote that hearing the soldier giving instructions to the Palestinian was "unbearable."
"I believe that every person has the right to free and respectable living, and we are all equal. I believe the Israeli occupation corrupts the Israeli soul," she said.