The protester, who was wearing a white shirt that read ‘End UK Private Jets’, ran onto the pitch at the O2 Arena and briefly set his right arm and part of the pitch on fire.
Security ran towards the protester to choke him with what appeared to be a suit jacket.
The protester has been arrested and the case is being handled by police, the Laver Cup said in a statement to CNN.
The protester was escorted off the pitch by security and the match resumed after a short delay. The protester appeared to be fine.
Tsitsipas then defeated Schwartzman in straight sets.
The match took place before tennis great Roger Federer started his last competitive appearance in the same competition and at the same venue.
The Laver Cup sees teams from Europe and the rest of the world compete in nine singles matches and three doubles matches over three days.
