Ms McDonald said she will not attend the event at the White House over "a principled stance against the threat of mass expulsion of the Palestinian people from Gaza" - a reference to recent comments by US President Donald Trump.
"Everybody I've spoken to loves the idea of the United States owning that piece of land, developing and creating thousands of jobs," Mr Trump said, adding that Gaza could become "the Riviera of the Middle East" where "the world's people" could live.
"We are all heartbroken whenever we witness the suffering of the Palestinian people, and the recent comments by the US president around the mass expulsion of the Palestinian people from Gaza is just simply something that I cannot ignore.".
Mr Trump did also not rule out sending US troops to the region, and said the US would "develop" Gaza and create "thousands and thousands of jobs".
The US president called Gaza a "demolition site" and said the two million Palestinians who currently live there could go to "various domains" - and that his "takeover" plans would not include a right of return for those who left.
