Ings claims Cherries should have been awarded a second-half spot-kick when Saturday's League One derby at Dean Court was delicately poised at 1-1.
The striker was sent sprawling by a 61st-minute challenge from Saints defender Jose Fonte, although referee Andre Marriner waved away Cherries' appeals.
Marriner, a Premier League official, deemed Fonte's tackle as fair, even though he angered the Dean Court faithful by awarding Saints a goal-kick rather than a corner to Cherries.
Cherries had two loud penalty claims turned down during their 2-0 defeat at St Mary's in October with both Saints goals coming from hotly-disputed spot-kicks.
Ings told the Daily Echo: I definitely thought it should have been a penalty. I cut across him and he took out my back leg which forced me down. I'm not one to go down in the penalty area when I'm in front of goal because I like to score goals.
There was no need for me to go down. He either tackled me and got the ball or he fouled me and it should have been a penalty. It should have been either a corner or a penalty the latter in my opinion and I don't know why he gave a goal kick.
Ings, who described Marriner's first-half display as brilliant, added: If we had been given a penalty and scored it, it could have been a turning point for us. I can't say we would have kicked on and won but I'm sure it would have been much closer.
The scoreline makes it look like we got smashed but it wasn't like that at all. We gave it a really good go and were worthy of at least a point. I thought we were very hard done by.
The lads put their heart and soul into every minute and, if a few decisions had gone the other way, it could have been different.
Defeat saw Cherries drop to fifth, two points behind second-placed Huddersfield and eight clear in a play-off berth. The chasing pack is headed by Leyton Orient who have three games in hand on Cherries and four on sixth-placed MK Dons.
Ings added: We need the supporters to stay behind us because we need them more than ever now. Our performance against Southampton showed we have still got a lot of fight in us and anything can happen over the closing weeks of the season.
Discussing the penalty incident, Cherries boss Lee Bradbury said: Danny is not the type to go down and wouldn't have gone to ground unless he had been taken down.