BERLIN (REUTERS) - Chancellor Angela Merkel said on Wednesday (Aug 23) that Donald Trump must be shown appropriate respect for holding the office of the US president, even if she may differ with him on policy issues.

Merkel, campaigning for a fourth term in office after a Sept 24 national election, has refused to bend to pressure from her Social Democrat (SPD) rivals to resist demands by Trump for Nato members to increase their defence spending.

As a committed Atlanticist, she has stressed the strength of German relations with the United States even when flagging differences in opinion on policy.

"If you take the president of the United States, whatever differences of opinion there may be, I know he prevailed in a tough election. It wasn't reserved for him on a silver platter," she told business daily Handelsblatt in an interview.

"In the end, he won the election under American electoral law and that means he is democratically elected and that this person should be shown the appropriate respect, regardless of how I assess his views," she added.

Her SPD challenger, Martin Schulz, has been far more critical of Trump, referring to the US president as "this irresponsible man in the White House".

Merkel, who enjoyed holidaying in the United States before becoming chancellor in 2005, said she missed the opportunity to vacation there now.

"I can't go on holiday in San Diego now as chancellor because the time difference is too much, and that is something I miss a bit, but the work itself is so marvellous that I can afford to miss it."