Doubt has lingered over both players' futures at Camp Nou, particularly in the case of Iniesta as he has repeatedly confessed to being unsure whether he will stick around beyond next summer.
Terms appeared to have been agreed with Messi in July, when the club announced in a statement that he had extended his deal until 2021, but a formal contract signing has yet to be arranged.
"Messi? He has a four-year contract. He's the best ever and played for us since he was small and we enjoy watching him play because he's unique," he told reporters. "Contracts for Messi and Iniesta? The club members can rest easy. We've already said Messi's renewal is signed and that he'll be at Barca for as long as he wants, the same with Iniesta.
"[Iniesta] has extraordinary quality. He was here when Ronaldinho was and now he's with Messi. He's crucial for us, he had a great game. Starting with three wins and conceding none is something that hadn't happened for years. We've started with enthusiasm and excited the club members. It's to Ernesto Valverde's credit."
As things stand, both players are due to be out of contract in Catalonia next year.