"Members of the so-called Last Generation sprayed the columns on the east side of the Brandenburg Gate with orange paint from fire extinguishers during the morning," Berlin police said on X, formerly known as Twitter.
Police officers saw a hydraulic lift was being used at the gate and kept the protesters from scaling the structure, officials said.
Police arrested all 14 protesters at the site and launched an investigation into property damage.
The Last Generation, a German group within the Europe-wide A22 network, which includes Britain's Just Stop Oil, has made headlines in Germany with hundreds of road blocks by protesters who glued themselves to the tarmac.
Their actions have led to a law-enforcement crackdown by Germany's federal states.
Climate activists glue themselves to artworks in protest - in pictures
The Last Generation posted pictures of the spray-painting on X.
"We will not stop our protest unless a pivot is initiated. We have to exit oil, natural gas and coal by 2030 at the latest," it said.
Germany aims to reach net-zero emissions by 2045, but it missed annual targets for the past two years.