Tottenham boss Mauricio Pochettino says he "crossed the line" and might apologise to referee Mike Dean for approaching him on the pitch after Saturday's defeat at Burnley.
Pochettino complained about a corner awarded in the build-up to Burnley's opening goal in the 2-1 loss.
He argued with the fourth official during the match and Clarets defender Phil Bardsley had to pull him away when emotions spilled over at full-time.
"I made a mistake," said the Argentine.
Pochettino said the "emotion and disappointment" of the defeat led to a reaction which was "not normal".
The result meant Spurs, who are third, missed their chance to move two points behind Premier League leaders Manchester City and second-placed Liverpool.
The Clarets opened the scoring shortly after half-time when Chris Wood headed in Dwight McNeil's inswinging corner.
Spurs striker Harry Kane - making his first appearance since 13 January - equalised after latching on to Danny Rose's quick throw-in and poking past Tom Heaton, but Ashley Barnes tapped in Burnley's second late on.
"We know how important the match was and we felt disappointment," said Pochettino.
"I should have gone to the dressing room and got some water. A stupid thing happens and you react. Maybe I will go and apologise to the referee.
"We lost because of our mistakes, not to find an excuse or to blame things not in our hands. We should do better and in the end we need to blame ourselves.
"I said this game was key and that if we didn't win we cannot think we are a real contender [for the Premier League title].
"It is a massive opportunity lost."
'We failed to show our credentials'
Tottenham, who are yet to draw a Premier League game this season, beat Chelsea 3-1 in the league before a 2-0 north London derby win over Arsenal in the quarter-finals of the Carabao Cup in December.
However, as well as Saturday's defeat at Turf Moor, they have lost league games to Watford and Wolves.
"We can beat Chelsea and Arsenal but if you want to make history, you must win these kinds of games," said Pochettino.
"It is not about tactics, or selection. You have to come here and fight.
"The game was never under control for us. We conceded, then we scored. We created some chances, but not enough.
"If you want to be a contender, you need to come here and show your credentials and deserve to be here - but it did not happen.
"We need to find why - but inside, not outside."
BBC Sport's Simon Stone:
This was being billed as a weekend when Liverpool could really find their rivals snapping at their heels.
However, instead of Tottenham being two behind them heading into Sunday's game at Manchester United, they have a chance to open up an eight-point gap on Spurs.
With the Premier League lead on the line, what an incentive for Jurgen Klopp's men to win at Old Trafford.
Former Arsenal defender Martin Keown on Match of the Day:
You can forgive Mauricio Pochettino for that. I think he is exemplary in the way he manages that club. He went below the line today but that's his passion.
When he reflects upon it he'll realise his team didn't really work hard enough.