Health Minister Jose Angel Cordova said that the virus appeared to have peaked between 23-28 April.
"The evolution of the epidemic is now in its declining phase," he told a news conference.
President Felipe Calderon, meanwhile, denounced what he described as "discriminatory measures" against Mexicans by some countries "because of ignorance and misinformation".
He did not name any countries but his remarks came after Mexico criticised China for placing in quarantine up to 70 Mexicans, even though they had shown no sign of having contracted swine flu.
Mexico said it was planning to send a plane to Beijing to pick up the Mexicans.
China denied it was being discriminatory. "This is purely a question of health inspection and quarantine," the foreign ministry said.
More than 300 guests at a hotel in Hong Kong have also been under quarantine for a week after a fellow guest contracted the disease.
One guest, Kevin Ireland, spoke of a "sense of paranoia" initially by the authorities - who tackled the Sars outbreak in 2003 - but added that "there's no restriction on any kind of interaction" among the guests.
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