It looks like Donald Trump has successfully pissed off one of the first diplomats he was scheduled to meet as president. On Thursday, Mexico's president announced in a tweet that he would not be meeting with Trump next week, as previously planned."This morning we told the White House we won't attend next Tuesday's meeting with @POTUS," President Enrique Peña Nieto tweeted. "Mexico reiterates its will to work with the US to achieve agreements for both of us."Peña Nieto's tweet follows a video he released Wednesday night condemning an executive order Trump signed that day that would use federal funding to start construction on a border wall between the US and Mexico. Throughout his campaign, Trump vowed to make Mexico pay for the wall, and has said that while construction will initially use federal funds, he will get Mexico to reimburse the US for it eventually.Peña Nieto has made it abundantly clear, though, that's not going to happen, reiterating in his video message Wednesday, "I regret and reproach the decision of the United States to build a wall that for many years, far from uniting us, has divided us. Mexico does not believe in walls. I've said it many times before—Mexico will not pay for a wall."As of Thursday morning, the two had still been set to meet next week, but Trump apparently threatened to cancel it altogether, tweeting, "If Mexico is unwilling to pay for the badly needed wall, then it would be better to cancel the upcoming meeting." Looks like Peña Nieto agreed with him on that.