Peter Pawlett and Marc McNulty passed up the best chances for Tam Courts' visitors, while Eamonn Brophy's volley for the home side was ruled out for a foul.
The result leaves Jim Goodwin's men still seeking their first league win of the season.
Goodwin made three changes from the side that drew with St Johnstone. In came 16-year-old Dylan Reid for his first start, replacing the suspended Ethan Erhahon, and debutants Matt Millar and Connor Ronan as Richard Tait and Charles Dunne also dropped out.
United were beaten by Hearts in their previous outing and Courts made five changes from that line-up, giving debuts to Ilmari Niskanen and Scott McMann. Pawlett, Calum Butcher and Ian Harkes also started, with Jamie Robson having left the club and Dylan Levitt, Nicky Clark, Adrian Sporle and Chris Mochrie all dropping out.
Niskanen could have made an impact with the first United attack of the game but dragged his shot wide of target.
The visitors came closer with the first clear-cut chance of the game midway through the first half. Pawlett's run created the chance for McNulty and when his shot was partially saved, defender Joe Shaughnessy had to look alive to head the dropping ball over the crossbar.
Pawlett then missed an even better opportunity moments later when he thrashed his shot high over the bar after being picked out by McNulty.
It was one-way traffic late in the first half and Charlie Mulgrew was next to threaten with a free-kick that Jak Alnwick grabbed.
St Mirren finally registered a shot of note early in the second from Jamie McGrath, whose effort was well wide.
The home side then thought they had made the breakthrough after an hour when Brophy volleyed in a header from Curtis Main, only for referee Colin Steven to rule it out for a foul.
United were next to threaten in an increasingly open game through substitute Louis Appere, whose drive was deflected wide.
And the visitors really ought to have scored after 71 minutes. McNulty sprung the offside trap and raced through on goal but the striker somehow slid his shot wide of the post.
It was end to end now, with St Mirren having the bulk of the pressure and United threatening on the counter.
Tait thought he had made the breakthrough with a snapshot only for Trevor Carson to pull off a brilliant save.