Anthony O’Connor scored for the second match in succession, tapping in at the far post after Bobby Reid’s 54th-minute corner landed at his feet from a near-post flick-on.
Adebayo Azeez replied in the 63rd minute from close range, though, after goalkeeper Luke McCormick had saved substitute Craig Tanner’s initial shot.
Dons keeper James Shea then made a string of superb stops to play-off chasing Plymouth a winner.
Sheridan said: “I’m gutted we didn’t get the three points. I think the performance deserved three points.
“That’s probably the best we’ve played in a while. We created the opportunities but the keeper’s made some great saves and on other occasions we haven’t hit the target or when we did, we could’ve done better.
“We get the goal and I could not see them scoring. I thought we were going to go on and win it. I was very pleased with the way we played. It was a good response and I thought there was a bit more tempo to us.
“I thought Bobby Reid was outstanding – he ran the show. It’s just a crying shame to not get three points because we know the importance of getting them, but we move on.
“We’re still there in the top seven and we would’ve loved three points, but if anyone’s telling me we haven’t deserved to win, they’re watching a totally different game to me.
“I told all the players in there that it was a really good performance. We’ve just got to stick together and believe that we will be in the top seven come the end of the season.”
AFC Wimbledon boss Neal Ardley settled for a share of the spoils, even if their long wait for an away success continued.
Ardley added: “There were two teams out there wanting to win. We haven’t won away from home this year and we are desperate to get that win and they don’t really want to draw at home in the position they are in.
“I thought at times it was like a tennis match – an end-to-end game which was quite an exciting game to watch if you were a neutral.
“I was frustrated with how naive we were at times. We nearly got punished. We showed great energy and spirit and we have the makings of a good team.
“We work so hard on set pieces and it was disappointing to concede a goal like that. We have been decent at it this season, but as of late we have conceded a couple of set pieces which have cost us.
“We have gone behind away from home and we kept going. Our keeper James Shea was excellent and we got in some good positions and just lacked a bit of cutting edge.
“I am pleased for Ade – he needed that goal. We had to defend our box well, they are a good team going for the play-offs so you expect it and James played really well.
“All in all it is a good point but we are desperate to win a game. It was probably a point neither team wanted.”