BERLIN — Reflecting mounting European anger and astonishment at President Trump, several countries on Sunday rejected — sometimes in blunt terms — his ban on all refugees and the citizens of seven Muslim-majority countries entering the United States.

The spokesman for Chancellor Angela Merkel of Germany said there was no justification for the policy — not even the fight against terrorism — of refusing to admit refugees fleeing war. Prime Minister Theresa May of Britain revised her stance on the American directive to take a harder line, while Prime Minister Paolo Gentiloni of Italy said that Mr. Trump’s approach ran counter to basic European principles.

Steffen Seibert, a spokesman for Ms. Merkel, said in a statement that she had reminded Mr. Trump during their telephone conversation on Saturday that the Geneva Convention on refugees obliges all member states to take in those fleeing war.

The chancellor “is convinced that the resolute fight against terrorism does not justify blanket suspicion on grounds of origin or belief,” Mr. Seibert said, a day after Ms. Merkel and Mr. Trump talked at length for the first time since his inauguration on Jan. 20.