Diplomats are engaged in talks in Minsk and Washington
The United States has denied ordering Belarus to withdraw its diplomats and shut its embassy and consulate after Minsk expelled 10 US diplomats.
State department spokesman Tom Casey told reporters that while the US had "serious concerns", no decisions had been made "at this point".
The Associated Press reported earlier that Washington had ordered out Belarus's last six diplomats.
It said that Belarus had been given until 16 May to shut its two missions.
Relations between the two countries have become increasingly strained over US criticism of Belarus's human rights record, the BBC's Jack Izzard reports from Washington.
Diplomatic relations between the two countries have been going from bad to worse, our correspondent says.
The US has been critical of Belarussian President Alexander Lukashenko for his harsh treatment of opposition figures.
In early 2005, the US called the former Soviet republic Europe's only remaining "outpost of tyranny".
"At this point we have not made a decision to formally ask them [the Belarussians], or informally ask them, to reduce staff further," Mr Casey said.
"We have not made any decisions at this point."
He added that there had also been no decision to close the US embassy in Minsk.
Reporting Mr Casey's statement, AP said the US had "abruptly backed down" on its decision to order the closure of embassy and consulate "just minutes before American diplomats were to inform Belarus of the move".
It quoted unnamed US officials as saying orders had been prepared to tell Belarus it had until 16 May to withdraw its six diplomats.
By its decision on Wednesday, Belarus expelled most of the American diplomats based in Minsk, a move Mr Casey described as "unwarranted and unjustified".
The Belarussian foreign ministry has said that, at a meeting in Minsk on Thursday, US Charge d'Affaires Jonathan Moore confirmed those US diplomatic staff "declared personae non gratae would leave the Republic of Belarus at a specified time".