Porto boss Sergio Conceicao said Arsenal manager Mikel Arteta insulted his family in the loss to the Gunners in the Champions League last 16.
The Gunners went through to the quarter-finals after a 4-2 penalty-shootout victory thanks to two saves from David Raya.
"What Arteta said, towards the bench in Spanish, he insulted my family," Conceicao said in the news conference.
Arsenal club sources have said that Arteta denies the accusations.
After the final whistle the two managers appeared to have an intense discussion on the pitch before being separated.
"He should focus on training his team," said Conceicao.