A day after picking up a Golden Boot award for scoring 46 league goals last season, more than any other player in Europe, the 26-year-old Messi paid respect to his Real Madrid rival.
"I don't know if Cristiano Ronaldo is at his peak but he is always there scoring goals in all the games and taking part in his club and national side," Messi told Spanish sports daily Marca and other European sports journalists.
"He has been doing that for many years and whether he is at his peak or a bit less makes no difference."
The 28-year-old Ronaldo is emerging as the favourite to pick up this year's Ballon d'Or for the world's best player over four-time winner Messi.
Ronaldo scored a hat-trick on Tuesday as Portugal beat Sweden to qualify for their fourth straight World Cup finals and he tops the Spanish league scoreboard so far this season with 16 goals in 13 matches.
Messi has 11 goals from eight games in the league this season but has been sidelined for up to eight weeks with a muscle tear in his left hamstring muscle, his third leg injury this season.
Spanish Prime Minister Mariano Rajoy, a Real Madrid fan, told public radio he would back Ronaldo for the Ballon d'Or award if he had a vote.
"I think he is in impressive form. He is a player who gives everything, who makes an all-out effort. Yes, I would vote for him," Rajoy said.
The Portuguese's chances seemed to rise even further when FIFA announced this week a two-week extension to the voting deadline until November 29, citing a weak turnout, and allowing participants to change ballots already cast.
Catalan sports newspapers, which traditionally back Barcelona, cried foul over the FIFA decision, which comes as Ronaldo hits top form and Messi is injured.
Messi brushed off comments in the media about the injuries he has picked up this season, following some criticism that he should have paced himself better.
"What they say about the injury did not worry me and does not worry me because I am used to people talking and saying many things not only about the injury but about pretty much everything," he said.
"I am sorry I cannot help my team-mates now but it is an injury that heals normally and I will be back next year keen to get started."
The Argentine international said there was no chance of his leaving Barcelona despite suggestions that some clubs would be ready to write a blank cheque to sign him.
"My intention is to stay with Barcelona for good," Messi said.
"I am grateful if what they say is true and there are people interested. It makes you proud that they say such things. But my life is with Barcelona."
Despite picking up four World Player of the Year awards, three Golden Boots, and with Barcelona a string of Liga, Copa del Rey and Champions League victories, Messi said he still dreamed of winning the World Cup with Argentina.
"I have had the fortune of winning all the individual and club awards. Getting the World Cup would be a dream for me, for my team-mates and for a whole country that has not won in a long time," he said.
Argentina have big hopes, Messi said.
"We aim to arrive in top form to win the World Cup, which is the dream for the whole of Argentina," he said.
Asked about Argentina's biggest rivals, Messi said Brazil, Germany and Spain were widely seen as World Cup favourites, "and then there is always a surprise team that appears".
For the Champions League, Messi said he saw Real Madrid and Bayern Munich as Barcelona's most serious challengers.