File Photo: State Department spokesman Ned Price speaks during a news conference at the State Department, Tuesday, Feb. 23, 2021, in Washington. AP
The State Department blamed logistical issues but said it considered the Russian-led forum "constructive."
"We look forward to engaging in that forum going forward, but we're not in a position to take part this week," State Department spokesman Ned Price told reporters Monday.
Russian envoy Zamir Kabulov on Friday announced the four-nation talks in Moscow, saying they would aim to "work out a common position on the changing situation in Afghanistan."
Russia, China and Pakistan have been among the most active nations in engaging the Taliban since the Islamists took over Afghanistan in August during the US pullout after 20 years of war.
The United States has been encouraging nations not to recognize the Taliban government, hoping for leverage on key issues of concern including the rights of women and girls.
Price declined to explain the logistical issues that prevented the United States from attending.
The talks come amid an intensifying dispute over the number of diplomats the United States is allowed to accredit in Moscow, although Presidents Joe Biden and Vladimir Putin at a June summit agreed to seek cooperation where possible on other areas.