After three league defeats, Ross delivered a dominant display to overcome their visitors from Paisley and secure their first win of the campaign.
Lennon said: "We knew it would be challenging coming up here. Apart from Celtic, Ross County had the best home record last season. But I thought we were ready for that challenge - we started all right, there was a lot of pleasing stuff throughout.
"The over-riding emotion just now is we are all very frustrated.
"We have a lot of quality and character in that dressing room, a lot of players who can turn a game - potential match-winners.
"But we also have players out there that are costing us with lack of concentration.
"We have to make sure we overcome that. We have certainly created enough opportunities over the last couple of games in the final third but we are just not getting over the line."
Lennon is confident his side will overcome their slow start to the season.
He added: "The goals we are conceding are very disappointing and frustrating. But I believe in the group of players we have and we will come through this difficult time together."