The comment is a reiteration of his long-held position but the first time he has spoken at length on the topic since speculation of European bank mergers heated up in recent weeks.
"Consolidation needs to happen in Europe," Sewing was quoted as saying. "It's important that we're not a junior partner."
Last year, Deutsche Bank called off merger talks with its smaller domestic rival Commerzbank. It also briefly explored a tie-up with Swiss lender UBS.
Sewing told Bloomberg TV that he was "laser-focused" on his current strategy but that if the bank's share price were to recover "we then have a different position, a better position" in considering big deals.
Deutsche Bank shares hit a record low earlier this year but have since bounced back to gain 6.4% so far this year.
Last month, Deutsche Bank's finance chief James von Moltke underscored the logic behind big bank mergers and said the bank was preparing to "engage in merger activity when the time comes and the right opportunities arise".
(Reporting by Tom Sims; Editing by Riham Alkousaa and Louise Heavens)
