Adjei, 42, and the Go Ahead Eagles staff went out after the Eagles won their first game since November on Sunday, when they beat Heracles Almelo 4-0.
Videos of Go Ahead Eagles manager Melvin Boel singing songs in a Deventer bar did the rounds, as well as rumours of Rick Adjei being arrested in a bar. The club confirmed on Monday that Adjei had been taken into custody and released shortly thereafter.
"A discussion arose between Adjei and the bar staff at the café in question, which ultimately led to an unpleasant situation. The club regrets this, but also expresses its disappointment at the speculation currently circulating on social media," Go Ahead Eagles said in a club statement.
"Due to the further course of events in the café in question, the police were called in. Adjei did not fully cooperate with the police's request, after which it was decided to take him to the police station, where the assistant coach received a fine. Not much later, he returned home."
A misunderstanding
Adjei, who joined Melvin Boel's staff last summer, said he regrets the situation that arose at the café.
"I believe it was a misunderstanding. It was an enjoyable evening, but unfortunately, an incident arose at the end, which was a shame. Ultimately, it turned out to be nothing serious and could have been prevented by both parties."
The situation is not expected to have any consequences for Adjei's future at the club.