The Serie A champion reportedly paid €36 million ($52.6 million) to sign attacking midfielder Charles De Ketelaere from Club Brugge, and also brought in striker Divock Origi on a free transfer after his Liverpool contract expired.
But it has been a quiet transfer window for the Rossoneri after they ended an 11-year wait to win the Scudetto last May.
Milan starts the defence of its title against Udinese at San Siro on Sunday (AEST) and head coach Pioli hopes to have more new faces on board by the time the transfer window closes on 1 September.
He said: "I am very happy and delighted with who has arrived. If there is a chance to improve the squad, we will not back down."
Pioli added: "The transfer market can offer you situations that you may not have thought of until now. If there is the possibility the squad will be improved; different characteristics may be needed from those we have."
Such a hectic schedule because of the FIFA World Cup in Qatar will provide further challenges, but Pioli is relishing another title battle.
He said: "It will be a special season. Today I showed the team the whole calendar until 13 November and many will have 23 to 24 games in 90 days.
"I will need everyone available. In three months we will have already played a lot: we play 15 league games, the [UEFA] Champions League.
"It will be a very balanced championship and I think it will be difficult for everyone to improve the standard of the last championship. All the top eight are at a high level, the mid-table ones have grown. It will be a good fight."