“The gruesome shooting in Orlando has made a deep impression on us here in Norway. My thoughts go to those who have lost their lives and their families. A brutal and senseless attack on people's free and happy lives,” Solberg wrote on Facebook.
The Norwegian PM also issued a short English-language message via Twitter in which she said she was "horrified" by the "senseless brutality against innocent people".
The Sunday massacre at a gay nightclub in Orlando was the deadliest mass shooting in recent US history, killing 50 and wounding at least 53 others. The American-born gunman, who was shot dead by police, pledged allegiance to the terrorist group Isis shortly before the attack.
Speaking to broadcaster TV2 on Sunday evening, Solberg stopped short of calling the shooting an act of terror.
“Unfortunately there are a lot of hate crimes against homosexuals throughout the world and this attack was aimed at a place for homosexuals,” the PM said. “At the same time, we mustn't draw conclusions before the police are finished with their investigation.”
Solberg said that she did not see a need to increase security at this weekend's Oslo Pride events.
“I don't think it is necessary to have extra security precautions, but that it is a decision that the police must make,” she told TV2.
“We must work together to stop extremism. Violence is never the answer,” Solberg added.
Norway is just a month away from the five-year anniversary of its worst mass killing in modern history. In July 2011, convicted domestic terrorist Anders Breivik killed 69 and injured another 66, many of them teenagers, in his attacks on downtown Oslo and the island of Utøya.