Van Persie was angered at a silly yellow card picked up by Diaby, who also lost control in February when receiving a red card and helping to spark a comeback for Newcastle in a 4-4 draw at St James' Park.
It is reported that the Dutchman had to be pulled away from Diaby in the away changing room at Bloomfield Road, but Wenger says he welcomes the passion shown by Van Persie.
"They are two good friends first of all, who get on very well," Wenger said. "Van Persie was concerned about Diaby getting a yellow card and what would happen if he got a second ... we all know what happened at Newcastle [when Diaby was sent off].
"Diaby accepted it and said okay. Of course, I'm pleased [about the passion]. I never was worried about the mentality of the team. This team is focused. Unfortunately we have been hit very hard but we have not been out of every competition early on having not performed.
"This team has given absolutely everything to perform in every competition and we are still today in the championship race. Many times our leadership has been questioned but they go away to the national team, they're all captains.
"Rosicky, Nasri has been captain of France, Fabregas is captain here, Van Persie has been captain here, we have plenty. Vermaelen has been, Squillaci has leadership qualities, Lehmann in goal - you think he has no voice?"