An assistant referee was struck by a firework thrown from a section of Tottenham supporters during the London side's Barclays Premier League game at Aston Villa.
The restart after the 31st-minute goal was delayed after the incident but Bryan, who appeared to have been hit on the back of the neck, was fit to continue.
The Football Association and the Premier League, who have issued warnings about flares this season, are likely to investigate.
The incident was captured by a television camera.
A fan was led out of the stadium by police and stewards soon afterwards.