Jamie Vardy’s goal in the 80th minute secured victory for Brendan Rodgers’ side on Sunday evening.
But Lacazette was unlucky not to have put Arsenal in front after his near-post header from a corner was ruled out as Granit Xhaka was deemed to be standing in an offside position.
The French striker has faced criticism from Gunners supporters over his performances in recent weeks.
But Arteta had no issues with Lacazette’s display against Leicester.
‘Obviously, strikers need goals and he started tonight, he looked sharp and he was really aggressive in his play,’ said Arteta.
‘Yeah, he had an opportunity to score that goal and he didn’t.
‘I just support them and give them more confidence and [help them] try to create more.’
Arteta also believes the defeat was ‘harsh’ on Arsenal.
‘I was really pleased with the first half, the way we pressed, the aggression we showed against a team that are very capable of breaking that pressure and creating chances against you,’ said the Arsenal manager.
‘We were very effective against that, we were on top of the game, we restricted to nothing, we had the right opportunities to attack good space and create some chances.
‘We scored a goal as well on a set piece, I don’t know how it was disallowed. Then after that in the second half against a really low block you have to be patient and not make any error because this is what they are waiting for, they just need a moment to catch you on the break or with some space and we made the decision when there is no pressure on the ball to try to attack that space and they scored a good goal.
‘After it was difficult in the last 15 minutes, even with three strikers on the pitch we didn’t manage to have enough continuity in our play and we have too many free kicks away, we didn’t put the ball as often as we could in the box.
‘But credit to them for what they have done but I think it is a very harsh result for us considering what happened in the game.’