MADRID, June 18 (Reuters) - The European Central Bank's vice president, Luis de Guindos, said on Tuesday that the best time to make rate decisions was coinciding with the release of the bank's updated macroeconomic projections, the next of which is slated for September.

The ECB lowered its key rate by 25 basis points from a record high to 3.75% on June 6, its first cut in five years. However, it raised its inflation forecasts and President Christine Lagarde declined to confirm it had entered a phase of "dialling back" its restrictive monetary policy.

"The projections are updated every three months, so we'll soon have new ones in September," De Guindos told Spanish state broadcaster TVE.

"Those are the most significant and interesting moments from the point of view of monetary policy, because our projections are a very important indicator when it comes to decide the evolution of interest rates," he added.

(Reporting by David Latona, editing by Andrei Khalip)