The two Russian intelligence agents were arrested last month and have been charged with assassinating former Chechen president Salim Khan Yandarbiyev in the Qatari capital Doha on 13 February.
"In the immediate aftermath (of the attack), Qatar requested that we send a small team of experts on technical aspects of explosives," a US embassy spokesman said.
"The experts played no role in the arrests" of the Russian agents, the spokesman said.
On Monday Steven Pifer, the US deputy assistant secretary for European and Eurasian affairs, told the Vremya Novostei daily that: "concerning the arrest of the Russians, we provided minor technical assistance to Qatar but for the most part, the Qataris acted themselves."
The comments set off protests in Moscow.
"In the immediate aftermath (of the attack), Qatar requested that we send a small team of experts on technical aspects of explosives"
US embassy, Moscow
"We can only regret that the United States did not give technical or political assistance to the international community to find Yandarbiyev and put an end to the criminal activities of that international terrorist," Konstantin Kosachev, the head of
parliament's foreign affairs committee, said on Monday.
Russia has demanded Qatar should free the two Russian agents, denying they had anything to do with the murder of Yandarbiyev.
Yandarbiyev died after his car blew up in Doha as he was returning home from Friday prayers.
The affair has turned into a full-blown diplomatic row. Moscow detained two Qatari citizens in transit on 26 February, in apparent retaliation, and is reported to be negotiating a swap.
Russia had accused Yandarbiyev of helping finance Chechen separatists who have been fighting a war since 1999.