"What are they trying to hide?" Obama asked.
Obama said the "immediate focus" in the aftermath is "on recovering those who were lost, investigating exactly what happened and putting forward the facts."
"We have to make sure that the truth is out and that accountability exists," Obama said.
Obama said Russia has "direct responsibility" to allow international access to the crash site in order for a proper investigation to take place.
"Now's a time for President Putin and Russia to pivot away from the strategy they've been taking," Obama said.
Putin has avoided taking blame for the crash, pointing a finger instead at Ukraine.
In his remarks, Obama also noted Secretary of State John Kerry had departed for the Middle East to push for "an immediate ceasefire" between Israel and Hamas in Gaza.
"We don't want to see anymore civilians getting killed," Obama said.
Below, more from the AP on the plane crash:
U.S. officials have been seeking to build a case that the plane was shot down by pro-Russian separatists in eastern Ukraine. Officials also say it is unlikely the separatists could have fired a missile without assistance from Russia.
The Malaysia Airlines plane was brought down Thursday with nearly 300 people on board.
The White House has been calling for an international investigation into the crash and a cease-fire around the area.
See more updates on the situation in Ukraine below: