Washington/London: Presumptive Republican nominee Donald Trump has said London’s new mayor Sadiq Khan could be an “exception” to his call for a temporary ban on Muslims entering the United States. Khan has rejected Trump's offer. Khan, a Muslim, was elected to run the British capital last week. On Monday, Trump said he was “happy to see” that Khan was voted in, according to the New York Times. Asked about how his proposed ban would affect Khan, 45, who is also a member of Britain’s Parliament, Trump said: “There will always be exceptions,” the Times reported. “I think if he does a great job, it will really - you lead by example, always lead by example. If he does a good job and frankly if he does a great job, that would be a terrific thing,” Trump was quoted as saying. However, Khan rejected Trump's offer on Tuesday. "This isn’t just about me - it’s about my friends, my family and everyone who comes from a background similar to mine, anywhere in the world,” Khan said. “Donald Trump’s ignorant view of Islam could make both our countries less safe - it risks alienating mainstream Muslims around the world and plays into the hands of the extremists. Donald Trump and those around him think that western liberal values are incompatible with mainstream Islam - London has proved him wrong,” the Guardian quoted him as saying. Trump's "ignorant" views of Islam "could make both our countries less safe," Khan added. Trump called for the ban in December after Syed Rizwan Farook and Tashfeen Malik, a married couple, killed 14 people in a mass shooting in San Bernardino, California. The Islamic State said the two were its followers. In an interview with Time, Sadiq Khan said he would like to go to the United States to meet with American mayors. “If Donald Trump becomes the president I’ll be stopped from going there by virtue of my faith, which means I can’t engage with American mayors and swap ideas,” he said. He said he planned to visit the United States before January in case Trump wins the presidential race.