The State Department was unable to confirm whether the new March 31 meeting in Brussels will replace a planned foreign ministers' meeting that Tillerson will not attend on April 5 and 6.
Earlier this week, Tillerson caused dismay among Washington's European allies when his office announced that he would not be able to attend the meeting of the 28-member alliance.
But diplomats have been scrambling to find another date to accommodate the envoy from NATO's leading member.
Another official told AFP it was not yet clear whether the full foreign ministers' meeting would be brought forward to Tillerson's preferred date or if his talks would be separate.
Chinese leader Xi Jinping is expected to visit President Donald Trump in the United States in early April, and Tillerson would be expected to attend their meetings.
But his office has not confirmed that engagement, and Tillerson's refusal to attend the long-planned NATO talks has raised questions about the United States' commitment to its allies.