The move announced on Tuesday has already provoked fury in Turkey, which says the YPG are linked to its own domestic Kurdish separatist group the PKK, or Kurdish Workers Party.
Turkey is deeply opposed to the arms agreement and has called for its reversal.
The YPG statement is sure to raise controversy, as fears have previously been voiced by Turkey of the U.S. decision to arm the Kurds that they will stockpile weapons and will later use them to launch further conflict as well as terrorist attacks for the sake of their independence after Daesh is defeated.
Yildirim told reporters on Wednesday the us decision "will surely have consequences and will yield a negative result for the U.S.as well".
"The supply of arms to the YPG is unacceptable", Deputy Prime Minister Nurettin Canikli told A Haber television on Wednesday. "We can not accept the presence of terrorist organizations that would threaten the future of the Turkish state". We hope the USA administration will put a stop to this wrong and turn back away from it.
In Ankara on Wednesday, Erdogan, referring to the YPG, said the "fight against terrorism should not be led by another terror organization".
Erdogan's statement capped a day of alarmed comments by Turkish officials, with Foreign Minister Mevlut Cavusoglu saying "every weapon that turns up in their hands is a threat directed toward Turkey".
"YPG and PKK are both terror groups, there is no difference at all between them".
In a surprise announcement, the Pentagon had said Trump had authorised the arming of Kurdish fighters within the Syrian Democratic Forces (SDF) "to ensure a clear victory over ISIS in Raqa".
Pentagon spokeswoman Dana White disclosed little about Mattis' meeting with Binali in London, where both men were attending a conference on Somalia.
US forces were able to help the SDF conduct an airborne landing on the bank of the Euphrates River in late March, allowing them to win control of a critical airbase nearby, Reuters said. "We have very open discussions about options and we will work together, we will work out any of the concerns", he said.
Tabqa and the nearby dam, Syria's largest, were seized a day earlier in an offensive that lasted almost seven weeks, with the backing of airstrikes from the worldwide coalition. The YPG has a similar relationship with Russian Federation.
Reports indicate that Defense Secretary James Mattis approved the move following a request from U.S. Central Command.
Mattis' remarks to reporters traveling with him followed an approximately 30-minute meeting in London with Turkish Prime Minister Binali Yildirim, the highest-profile face-to- face conversation between U.S. and Turkish officials since the announcement. The dispute poisoned ties between Turkey and the United States under the administration of former president Barack Obama but commentators had hoped for a smoother ride under Trump.