It gave Kriener 48 hours to leave the country.
At the country's main airport, Kriener spoke to journalists and said he hoped the leader of the National Assembly would be safe.
The move against Weddle anxious several Venezuela analysts, who see little logic to Maduro's authoritarian attacks against individual journalists.
The U.S., Germany and some 50 other countries have urged Maduro to resign so the country can prepare for elections.
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.
Guaido denounces Maduro as an usurper whose re-election a year ago resulted from a sham vote.
German Foreign Minister Heiko Maas said European support for Guaido was "unwavering".
The U.S., which says Maduro's presidency is illegitimate, said Wednesday he must free the reporters.
Guaido's call toward Citibank comes amid the ongoing political and financial crisis in Venezuela, which escalated in late January when US-backed opposition leader Juan Guaido illegally declared himself interim president of the Latin American country.
About 3,000 Venezuelan children cross the border daily to attend school in Colombia, and the closure of border bridges has forced them instead to take perilous treks along illegal pathways.
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. But Venezuela's military is continuing to block the bridges with rock-filled shipping containers.
Venezuelan students walk into Colombia from Venezuela along the Tachira River.
'That's ultimately a decision for Venezuelans to make, ' Abrams said.
An American journalist who was detained in Venezuela on Wednesday by government officials has been released.
Weddle has reported from Venezuela for more than four years, most recently working as a freelance journalist for the ABC affiliate in Miami, Florida. The union said it hasn't been able to discover what crimes the men are accused of.
The station said Weddle's last contact was on Tuesday afternoon and attempts to reach him on Wednesday have been unsuccessful.
"One of the defining characteristics the Virginia Tech community is that Hokies look out for and support fellow Hokies", said Mark Owczarski, Assistant Vice President for University Relations at Virginia Tech.
Senator Rick Scott, a Florida Republican, wrote on Twitter that Weddle's arrest was unacceptable: "He must be released immediately and the US will not stand for this kind of intimidation!"