Freddie Ljunberg disagreed privately with Unai Emery, before the Spaniard was sacked as Arsenal manager last Friday, The Athletic reports.
It is believed that the bone of contention was Emery's tactics.
Emery was fired following a 2-1 defeat by Eintracht Frankfurt in the Europa League, with Ljungberg being named his successor on an interim basis.
Ljungberg, who had been Emery's assistant, took charge of his first game as boss against Norwich in the Premier League on Sunday.
The Gunners drew 2-2 with the newly-promoted side at Carrow Road.
Ljungberg's second game, will be against Brighton at the Emirates Stadium, with Arsenal looking for their first win in eight fixtures.