"This action represents a threat against Germany", Guaido told Der Spiegel after Caracas declared ambassador Daniel Kriener persona non grata.
The station's president said in a statement it can't reach Weddle and is concerned.
Kriener was reportedly among a handful of ambassadors who went to the airport on Monday to greet Juan Guaido on his return from a tour of Latin American countries that support Venezuela's right-wing opposition movement. "He could have Juan Guaido arrested as soon as he arrived...but that would probably inch us closer here to some type of military confrontation".
The United States and some 50 other countries have recognised Mr Guaido as the legitimate leader of Venezuela and have urged Mr Maduro, to resign so the country can prepare for elections. Germany followed suit in early February. "The worldwide community must prevent Venezuelan money from being misused to kill opponents of the regime and indigenous peoples", Guaido said in an interview with the German news weekly Der Spiegel.
Tensions are escalating by the day in Venezuela, where US -backed Guaido seeks to oust President Nicolas Maduro. Maduro says he is victim of an attempted coup.
"This is an incomprehensible decision, which escalates the situation instead of easing tensions", Maas said in a statement.
He had been living in Venezuela for more than four years as a freelance journalist.
Venezuelan leader Nicolas Maduro has cut ties with Colombia after opposition leaders used the neighboring Andean nation as a launching point for humanitarian aid meant to undermine his authority. Weddle also wrote a post on Twitter describing Guaido's return as "triumphant".
A German foreign ministry spokeswoman confirmed Venezuela had expelled the ambassador and that the ministry was consulting with its allies on how to respond, according to Reuters. A senior official in the administration of U.S. President Donald Trump said it had identified efforts by Maduro to work with foreign banks to move and hide money.
Foro Penal, a lawyer co-op that handles politically sensitive cases, said Weddle was held at a prison in Caracas alongside some of Maduro's fiercest opponents as well as five other American citizens - all of them dual nationals - who worked at Houston-based Citgo, a subsidiary of Venezuela's state-run oil monopoly.
According to the country's National Union of Press Workers, detentions have surged this year, with Camacho and Weddle joining 34 local and worldwide reporters, photographers and producers taken into custody in the past two months. The United States ratcheted up the pressure on Wednesday, with National Security Advisor John Bolton warning foreign banks that they could face sanctions if they participate in transactions benefiting Maduro.
Many were released after a few hours, although at least one reporter, German-born Billy Six, has been held since November on what his family says are trumped-up charges of spying.