He refused to take questions from reporters but displayed a photo that he said accurately portrayed the number of Americans on the National Mall Friday.
The photograph he showed was a non-aerial shot, taken from behind the podium, looking out at the crowds. Aerial photographs of the two inaugurations run Friday, taken from the same viewpoint but taken an hour apart on the respective days, showed a distinct difference in the number of people in attendance.
The Washington, D.C., Metro system was less inundated Friday morning than it was during Obama's first inauguration. As of 11 a.m. ET, the Washington Metropolitan Area Transit Authority said it had recorded 193,000 trips, compared with the 513,000 trips taken up to that time on Jan. 20, 2009. Some 317,000 trips were taken by 11 a.m. ET on Obama’s second inauguration on Jan. 21, 2013, the government agency said.
Spicer called the media "irresponsible" and said attempts to downplay the significance of the inauguration were "shameful and wrong."
He said new security measures slowed access to the National Mall.
"This was also the first time that fencing and magnetometers went as far back on the Mall, preventing hundreds of thousands of people from being able to access the Mall as quickly as they had in inaugurations past," he said.
According to law enforcement officials ABC News spoke with during the inauguration, the checkpoints and magnetometers were cleared of all lines before the inauguration ceremony began, and by the time the event started, there were no lines.
"The security perimeter for this inauguration was extended due to lessons learned and world events. Security fencing was placed around the National Mall this inauguration. There were seven access points where bag checks only were conducted," a U.S. Secret Service spokesperson said.
Those checkpoints on the National Mall -- the non-ticketed area -- had no magnetometers and were manned by TSA, Park Police and U.S. Secret Service personnel, who checked bags.
For the ticketed section this year, additional magnetometers were added to screen more people in less time, law enforcement officials said.
There were no significant problems with the flow of people through security checkpoints for this event according to officials, and attendees were cleared in time for the event.
In 2009, several thousand ticketed attendees were trapped in the 3rd Street tunnel -- the so-called "purple tunnel of doom" -- unable to get cleared through security in time to see the swearing-in.