The North London side sit top but their lead has shrunk to four points after a 3-2 home defeat to Manchester United, leaving them winless in three.
Mbeumo scored his eighth league goal to level before halftime, but late strikes from Patrick Dorgu and Matheus Cunha handed United the win.
Petit told talkSPORT, Petit said: "Yesterday I saw exactly what I thought about this player against Arsenal, it's Mbeumo. I think in terms of movement, he's very intelligent. He's got this flair in front of the goal. He's very good in terms of assists as well.
"I love his work rate. I love his behaviour on the pitch, technically, mentally as well. But more importantly, I like his movement, the link with his players all the time. He brings something different up front.
“He's not that physical, but in the meantime he puts everything he has on the pitch. But I love him because he's very intelligent.
"When I saw Manchester United buy him in the last transfer market, I thought, this is a good bargain."