The Catalan club had been unable to spend any more cash due to budget restrictions for 2016-17 running up until the end of June, but they are now ready to start bidding for the Italy international.
It was reported earlier this week by Barcelona-based sports paper El Mundo Deportivo that club chief Josep Maria Bartomeu will personally take charge of negotiations for the midfielder and those should start this week.
However, Barca believe Verratti is worth €80 million at the most and hope to close a deal for the 24-year-old for that price - just under the €81m they paid Liverpool for Luis Suarez in the summer of 2014.
Verratti - who is due to resume Paris Saint-Germain training on July 10 - is keen to join Barcelona and has rejected a lucrative offer of a new contract from the Ligue 1 giants. Whether he signs a renewal or not, however, PSG have no intention of selling the player this summer.
Any potential transfer could depend on the player, with some reports suggesting Verratti could go on strike to force through a move and PSG's strong stance may mean that is the only option if he really is determined to join Barca in time for the coming campaign.
However, Verratti is grateful to PSG and the club's fans for how he has been treated in his five seasons at the Parc des Princes and would prefer to reach an amicable agreement with the French side.
In the meantime, Barca have looked at other options, including former Tottenham midfielder Paulinho, but Verratti remains the Catalans' top target and the club will step up talks with PSG and the player's representative Donato Di Campli this week.
Barca made their first summer signing on Friday when they brought back winger Gerard Deulofeu in a €12m deal. The Blaugrana also hope to recruit a right-back, with Arsenal's Hector Bellerin their preferred player for that position.