WARSAW, POLAND—The Polish president has sharply condemned expressions of xenophobia and racism at a weekend march by nationalists, saying there is no place in the country for anti-Semitism and “sick nationalism.” It was the strongest and first unequivocal condemnation by a representative of the country’s conservative leadership of the white supremacist and racist views expressed by some of the 60,000 people who took part in a march on the Independence Day holiday Saturday in Warsaw.