Aguero, who scored a club-record 260 goals in 389 appearances for Manchester City, arrived at Camp Nou on a two-year contract after a free transfer from Pep Guardiola's team.
He was expected to link up with Argentina international colleague Messi before the Blaugrana legend departed on a free transfer himself to Paris Saint-Germain, Barca's financial issues preventing it from re-signing six-time Ballon d'Or winner after his contract expired, thus ending a 21-year spell at the club.
After Gerard Pique, Jordi Alba and Sergio Busquets agreed to pay cuts, Ronald Koeman's side was able to meet salary-cap restrictions and register Aguero and its other new signings.
The Argentina forward has now quashed any rumours that any so-called "Messi clause" was in his contract.
"I don't understand why there was talk of this," Aguero said. "When I signed, Leo [Messi] had nothing signed. They [Messi and Barca] were coming to an agreement.
"It was invented that there was a clause, but there was nothing.
"I didn't ask Leo much either, I didn't want to bother him.
"I saw him at the Copa America, he told me that they were about to agree, and I thought, good.
"But I didn't want to bother him every day either. I didn't speak any more after the Copa America and I was shocked when everything happened."
The 33-year-old enjoyed a stunning decade at City, but only managed seven league starts in 2020-2021, playing 559 minutes across 12 appearances.
His final campaign in the Premier League was hampered by coronavirus-related issues and injuries, but when Barcelona came knocking, Aguero could not refuse.
"When I was no longer at City and the talks with Barcelona came, I knew how the club was doing financially but I told my agent that I didn't care about money, that I wanted to come and play," he continued.
"Money is not a problem. What I was getting paid at City, I wasn't going to get paid here. Any player wants to play for Barca.
"Of course I would sign again, without a doubt. If someone from Barca calls you ... the name of the club ... many players are willing to give up money."