Obama acknowledged that suspicions still exist. But he added that Russian President Vladimir Putin has assured him that Russia is committed to help and that the two sides are looking for ways to improve counterterrorism co-operation more broadly.
"Obviously old habits die hard," he said.
Meanwhile, Secretary of State John Kerry is headed to Russia next week to meet Putin and Foreign Minister Sergey Lavrov. The talks are expected to touch on the attack in Boston and a host of bilateral tensions. The US and Russia are at odds on Syria, Iran and missile defense among other issues. Tensions have also spiked over the Kremlin's halt on US adoptions of Russian children and new Russian restrictions on civil society groups.
Kerry told reporters Tuesday his upcoming trip to Russia is "overdue."
Russia's co-operation in the Boston investigation is key, because the suspected bombers are Russian natives who immigrated to the US. Russian authorities warned US officials before the bombings that they had concerns about the family.
The April 15 bombings at the Boston Marathon killed three people and injured more than 260.