NATO Secretary General Anders Fogh Rasmussen on Friday condemned Syria's "infamous" crackdown on protesters, but said the alliance would not take action in the country, DPA reported.
Unlike in Libya, there was no United Nations mandate nor regional support for such an operation, he said in an interview with the Spanish national television channel TVE.
Rasmussen urged the Syrian authorities to "adapt to the legitimate aspirations of the people."
NATO had made progress in Libya, destroying more than 2,000 military installations and "saving countless lives," Rasmussen said.
He dismissed a comment by Libyan leader Moamer Gaddafi's son that the country would hold elections, saying the opposition would not accept that.
"I believe the only way to move towards a peaceful transition is for Gaddafi and his regime to leave power," the NATO chief said.
Rasmussen visited Spain on Thursday to hold talks with Prime Minister Jose Luis Rodriguez Zapatero, with whom he stressed the need to maintain pressure on Libya.