Senate Finance Committee Chairman Bob Dole (R-Kan.) urged President Reagan yesterday not to compromise on his three-year, 30 percent tax cut, but conceded "there are a lot of doubts" about the package and it could be altered visibly.

Dole said in an interview he fears that talk of compromise now might undermine his own panel's efforts to push the bill through, and said he has complained to the White House about officials' statements inviting a deal with Democrats.

At the same time, however, Dole suggested that the president's plan may face some resistance in the Senate, where he admitted ther is "a reservoic or proper skepticism" about whether the $52 billion tax cut would exacerbate inflation.

Although asserting it is too easly to predict the measure's outcome, Dole said there was pressure among Finance Committee members for subsituting portions of the tax-cut bill that the panel drafted last year for at least part of the Reagan proposal.

He said Finance Committee members now appear split over the Reagan tax-cut plan. However, he noted that there had "been a little shift" in favor of the plan since the president's budget victory in the House last week.

Dole's remarks suggested that the administration might not have as easy a time as some expected in pushing its tax-cut plan through Congress, even in the GOP-dominated Senate.

The possible substitutes the chairman outlined would push the tax bill decidedly closer to an measure the panel drafted last August, parts of which are being advocated by House Ways and Means Committee Chariman Dan Rostenkowski (D-Ill.).

Among the provisions Dole cited as possibilities were reducing the maximum tax rate for high-bracket individuals to 50 percent from the present 70 percent, easing the "marriage penalty" now in the tax code and liberalizing tax writeoffs for retirement savings accounts.

Dole also noted there was broad support within the panel for cutting the estate and gift taxes, another Reagan campaign promise. The Finance subcommittee already has held hearings on several such proposals.

Depending upon which versions are approved, the possible substitutes could amount do well over $10 billion to $15 billion, a price tag that seriously would erode the room being provided in the congressional budget resolution for the Reagan tax-cut package and force cutbacks in the president's proposals.

Dole also indicated he thinks Reagan will succeed in getting Congress to commit itself to cutting taxes for more than just a single year, but hinted it the lawmakers may not approve the full three-year reduction the White House wants.

He suggested that the Senate may enact a two-year tax cut instead or else provide for a "trigger" machanism that would allow the later-year tax cuts to take effect only under certain conditions.

Although Dole generally has supported the Reagan proposals, he has made it clear that he has reservations about the package, particularly on what impact it might have on inflation.

"I'm not a cheerleader for it," the Finance Committee chairman said of the three-year, 30 percent tax-cut plan. "I'm willing to be persuaded."

Dole's concern about talk of compromise appeared to center on statements by White House congressional liaison Max L. Friedersdorf this past weekend that "if I were Danny Rostenkowski, I would be coming in to talk with the president about his program and get the best deal I can before the tidal wave rolls over him."