Union Berlin have suspended David Datro Fofana for a week after he refused to shake his coach’s hand during the team’s Champions League loss to Napoli on Tuesday.

Fofana, who is on loan at the Bundesliga club from Chelsea, walked past Urs Fischer’s outstretched hand on Tuesday after the head coach substituted him in the 70th minute of their 1-0 home defeat to the Italian champions.

The two briefly made physical contact when Fischer appeared to jostle Fofana, who was replaced on the field by Kevin Behrens. The defeat was Union’s ninth consecutive loss in all competitions, and third in three Champions League matches.

Christian Arbeit, a Union Berlin spokesperson, said on Thursday that Fofana had apologised to Fischer and the club’s sporting director, Oliver Ruhnert. Fischer said he hoped Fofana would learn from the incident and that “it’s about accepting decisions.”

Fofana, who joined Chelsea from Norwegian club Molde in January for £8.7m plus add-ons, previously posted an apology to the Union team and supporters on Instagram, explaining he had wanted to stay on the field rather than be substituted.

“The gesture was not intended and in no way does it represent my attitude,” wrote the 20-year-old Ivorian. “All this was generated as a result of frustration because I wanted to continue helping the team to obtain a positive result.”

Fofana will train separately from the team during his ban and will not be considered for selection against Werder Bremen for the Bundesliga game on Saturday – or against Stuttgart in the German Cup on Tuesday – Arbeit said. He will rejoin team training on Wednesday 1 November.

After making four appearances for Chelsea last season, Fofana was sent to the Bundesliga club on loan in July. He is yet to score for Union in 11 appearances, with his most recent competitive goal coming in the Norwegian league last November.