Mayor Bill de Blasio showed solidarity with protesters Saturday at the G20 Summit.
He delivered the keynote address at a rally in Hamburg, alongside his son Dante.
"Our Earth depends on you. We will never stop fighting for our Mother Earth," de Blasio told those who attended his speech. "We will never stop fighting against racism and xenophobia."
The mayor pledged unity between New York and Germany, and praised both places for valuing freedom, tolerance, and diversity.
De Blasio also stressed that the city and country are committed to the standards that the Paris Climate Accord set, even though President Trump put the United States on the path to leave the deal.
Many of the G20 countries pushed forward with Paris Climate goals to tackle global warming in defiance of Trump's decision.
De Blasio caught some flak for leaving the country just one day after NYPD Officer Miosotis Familia was shot and killed in the Bronx.
The mayor's press secretary said the trip went on as planned because it did not conflict with Familia's funeral.
De Blasio is scheduled to return to the city Sunday.