Three bombing attacks rocked Yemen's capital Sanaa and Saada province during Friday prayers, killing at least 137 people and wounded some 350 others. The IS has claimed responsibility for the attacks.
"There is not, at this point, clear evidence of an operational link between these extremists in Yemen and ISIL fighters in Iraq and Syria," White House spokesperson Josh Earnest said, using an alternate acronym of the group.
Earnest said the US was investigating to determine whether there were "command-and-control structures" in place that may provide some evidence to substantiate the claims by the IS, according to Xinhua.
He also called into question the claim of responsibility by the IS in the attack in Tunisia earlier this week, noting that the group often makes such claims for propaganda purposes.
In a statement issued by the State Department on Friday, the US "strongly" condemned the suicide bombings in Yemen and deplored "the brutality" of the attackers.
"The way forward for Yemen must be through a political solution," State Department official Jeff Rathke said, adding that the US calls upon all Yemeni parties to return in good faith to a political dialogue to resolve their differences.
"Today's attack on the mosques in Sanaa underscores that terrorism affects all Yemenis and that no one political group alone can confront the challenges facing Yemen," Rathke said.