President Trump on Wednesday said Harvard should cap the number of international students it admits to create more spots for Americans, undercutting his administration’s argument that merit alone should guide admissions practices as it escalates its fight with the elite university. Mr. Trump’s comments came in response to a question about the Department of Homeland Security’s recent move to revoke the school’s ability to enroll foreign students. The college immediately challenged that decision in court, and a federal judge has temporarily blocked the policy. Still, the State Department has since halted interviews abroad with foreign citizens applying for student and exchange visas as the government expands its scrutiny of applicants’ social media posts, and Secretary of State Marco Rubio said on Wednesday that the Trump administration would begin revoking student visas for Chinese citizens. The policy shifts follow efforts to crack down on universities, including Harvard, over what the administration has said is a failure to address antisemitism on campus. Mr. Trump’s has also attacked policies aimed at supporting diversity, equity and inclusion in an attempt to bring academia more in line with his views that white men and those with traditional views of gender are being discriminated against.