The Argentine striker made his first appearance of the new season after four months out with an injury, coming off just before the hour mark in a game City won courtesy of a solitary first-half strike from Raheem Sterling.
But Aguero courted controversy just before half-time when he argued a decision with Massey-Ellis, having felt City should have been awarded a throw-in which was instead given to Arsenal.
As he remonstrated with the lineswoman, Aguero moved over and grabbed Massey-Ellis by the top of the shoulder briefly before she pushed his arm away.
Aguero received no punishment at the time but was criticised by supporters from both clubs on social media, while co-commentator Gary Neville said during broadcast: ‘He needs to be careful putting his hand on an official!’
The Premier League has previously stated it would clamp down on players disrespecting officials, but Guardiola refused to be drawn on the incident and defended Aguero’s character.
‘We can look at the problems in other situations but not in this one. Come on.’
Aguero had not played since sustaining a knee injury in June and Guardiola was delighted to once again be able to call on his forward.
He continued: ‘We are incredibly happy he is back, for him, for all of us. It was four months, still he is away from his condition, but he got 55, 60 minutes, that is good, and Wednesday we have another game.
‘So yeah it’s important to have him. We need his goals, his performance, and it’s good he’s back.’