PORTLAND, Ore. — Major League Soccer is lifting its ban on signs and banners featuring an anti-Nazi symbol for the remainder of the season and the playoffs.

A handful of fans in Portland were prohibited from attending matches this season after challenging a ban on the Iron Front, a symbol with three arrows pointed downward and to the left that was first used by an anti-Nazi paramilitary group in the 1930s. The league had said the emblem violated a ban on political displays included in the M.L.S. fan code of conduct adopted this season.

M.L.S. maintained the symbol is political because it has been appropriated by antifa, loosely organized militant groups of anti-fascists that sometimes engage in violence. Supporters’ groups maintain the Iron Front represents opposition to fascism and persecution — a human rights issue, not a political stance.

Portland Timbers and Seattle Sounders supporters’ groups, as well as the Independent Supporters’ Council, protested the ban, and some fans across the league continued to use the symbol on flags, banners and signs at games.