A small group of home supporters clashed with Lancers’ goalkeeper Tyler D’Cruz shortly before the end of the first half.
Both sets of players, management and referee Jonathan Wilks quickly diffused the situation, with play resuming soon after.
Jake Heryet’s stunning opener was cancelled out by a Liam Benson penalty – his second in as many matches – as it finished 1-1 at The Lashmar.
Lancers’ manager John Sharman admitted the scenes just before the interval were not nice to see and said: “There was a bit of an issue between Tyler (D’Cruz) and a small section of their support.
“The game was stopped briefly but quickly got back going again. Fortunately there was no issues at any other stage after that and we were able to complete the match.
“You never want to see something like that at any level. Myself, management and the players were over quickly to diffuse the situation.”
East Preston boss Bob Paine shared a similar view to Sharman following the incident.
He said: “It’s not something you want to see but it was quickly resolved. I’m not really too sure what happened exactly, play quickly got restarted and there were no further issues.”
Heryet’s thunderous volley fired East Preston ahead after 18 minutes. Lancing had chances and finally got back level through Benson’s spot-kick 25 minutes from time.
Alex Spinks was hauled down in the area, with a penalty awarded. Benson slammed the resulting spot-kick home – for the second time in as many matches – to make it 1-1.
Both teams had chances to win it in the closing stages but it ended all square.
Lancers boss Sharman came away pleased with a point.
He added: “I’d say a draw was probably a fair result. We had a couple of chances of getting the win after getting level but so did they.
“It’s another point gained at a difficult place on what was a difficult surface.”
Both clubs were weighing up what action to take at the time of going to press following the first-half incident. A report from the referee will be submitted to the Sussex Football Association.