The U.N. Security Council should hold a meeting about Trump's plans. This is just as bad as when Israel built that border fence with Palestine. Trump probably realized that he would not get his way in the meeting so he torpedoed it in advance rather than be embarrassed. The wall will not do a thing to stop illegal entry and anyone with a few brain cells knows it.
If Mexico's president wants to disrespect our president and refuses to meet, then he does so to his own and to his country's peril. If he refuses to meet, then Trump should have U.S. troops seize the border and impose martial law, and seize Mexican territory. Regardless of one's views on immigration, this is a country of laws and the laws are being flagrantly disobeyed, disrespected and enforced on a selective basis. For the sake of our financial security and physical well-being, we must be able to control our borders and if Mexico does not like it, then they will have a hard lesson to learn.
Donald Trump should not force a meeting and the best thing Mexico should do is completely ignore any more reference to this wall or relationship between the two countries. If President of Mexico would like to discuss this with Trump, he could but it will create more tension and it might not be the best thing right now.
Trump doesn't have the power to force the Mexican president to meet with him. As a matter of fact, I don't blame Pena Nieto for not wanting to meet with Trump. Trump thinks he has some ultimate power to force Mexico into paying for something they don't want and the idea is absolutely absurd.