Danny Lennon refused to blame goalkeeper Craig Samson for the 3-2 home defeat by Hibernian.
Samson gifted Hibs an early opening goal when he was caught trying to dribble his way out of trouble.
And the keeper was beaten from a very tight angle for the visitors' third goal in Paisley.
"Playing this brand of football, we will make mistakes, but we make mistakes together and Craig has saved us many times," said Lennon.
Leigh Griffiths was the man to profit from Samson's first gaffe, easily dispossessing the dithering keeper to shoot into an empty net.
But St Mirren, who made a very poor start to the match, found themselves in front on 34 minutes after two quick goals from Paul McGowan.
Just seven minutes later, Hibs were in front again thanks to a header from Sean O'Hanlon and a strike from Griffiths.
St Mirren bombared the visitors' goalmouth in the later stages of the second half but could not find an equaliser, although Hibs missed the best chance after the break, with Akpo Sodje missing an open goal from close range.
"We picked ourselves up and got into a deserved 2-1 lead only to self destruct again," groaned Lennon on BBC Radio Scotland.
"I've watched the second Hibs goal again and it's a blatant foul on Stevie Thompson. These decisions either go for you or they don't and it didn't go our way today.
"We gave Hibs a massive hand and, when you do that, it is sometimes very difficult to break down opponents.
"That was maybe the rub of the green Hibs needed. They maybe didn't deserve it in this one game, but sometimes across the course of the season these things happen.
"It is Danny Lennon who is asking the boys to play this way, so it is me who carries the can."
Ayr United visit Paisley in the League Cup on Tuesday and Lennon is looking forward to the opportunity of reaching a semi-final.
"You can still see that the fans were right there until the final whistle and they were very well entertained," he added.
"We have an opportunity on Tuesday evening to do the community proud and try to achieve a major cup semi-final and that will quickly turn what's been a poor afternoon for us into delight.
"But what we cannot afford to do is turn up the way we did in the first 20 minutes today.
"I must give our boys a great deal of credit for the second half and the way they took the game forward and we were very unfortunate not to take something from the game.
"I don't think we lost the match in the second half. I thought we just ran out of time."