Just Stop Oil protesters set off an orange flare next to the 17th green at the British Open on Friday before being driven off the course by the police in a golf buggy.
The incident happened as Corey Conners, Billy Horschel and Alex Noren walked up the fairway towards the green. American Horschel led a protester towards security officials and was cheered by other spectators.
Orange powder settled near the edge of the green just short of the putting surface but second-round play continued without any delay.
"A protester was quickly apprehended on the 17th hole and is one of four people who have been arrested by the police," organisers the R&A said in a statement.
"Play was not disrupted and we would like to thank marshals, players and other spectators for their vigilance and understanding as the protesters were removed."
Ground staff quickly cleared away the debris using leaf blowers.
Just Stop Oil protesters have disrupted several major sporting events in England this year including the Wimbledon Tennis Championships and the Ashes cricket test at Lord's.
Bearman handed 10-place grid drop for home GP
Teenager Andreeva marches into Wimbledon last 16
Liverpool players join family for Diogo Jota's funeral
Own goal propels Chelsea past Palmeiras into CWC semis
Sabalenka fights off Raducanu, Alcaraz marches on
