CAIRO (AP) — Riot police cracked down anew on demonstrators in Iran’s capital on Monday hours after the feared Revolutionary Guard threatened to crush any further post-election protests.A witness described an “air of sadness” marked by people wailing prayers into the night. Security forces used tear gas and fired live bullets in the air to break up a group of about 200 protesters paying tribute to a young woman whose apparent shooting death was captured on video and circulated around the world, witnesses said. The show of force came as the country’s highest electoral authority, the Guardian Council, acknowledged some irregularities in 50 districts — including more votes being cast than registered voters. But the council insisted the result of the June 12 presidential election was not affected. President Barack Obama defended his cautious approach with Iran’s leadership.