Watford manager Claudio Ranieri accused Arsenal's players of showing a lack of respect as the Gunners claimed a narrow victory in manager Mikel Arteta's 100th match in charge.
The in-form Emile Smith Rowe scored in a third successive Premier League game, sending Arsenal up to fifth in the table with a low drive from outside the box after 56 minutes.
However, prior to the goal Watford had put the ball out of play due to an injury and the hosts chose not to return possession from the resulting throw-in.
"When we put the ball out voluntarily, everyone expects [the opponent] to give the ball back to you but there was not that respect from the Arsenal players," Ranieri told BBC Sport.
Arteta responded: "I would say that we are the most honest team and in some stages we can even become naive."
The Spaniard added: "If he felt like that towards our club, I have to apologise if that's the case but I am sure there is no intention to take any advantage."